Rule

Federal Motor Vehicle Safety Standards; Occupant Crash Protection, Seat Belt Reminder Systems

A Rule by the National Highway Traffic Safety Administration on 04/06/2026

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• Public Inspection Published Document: 2026-06614 (91 FR 17144) Document Headings ###### Department of Transportation

National Highway Traffic Safety Administration

1. 49 CFR Part 571
2. [Docket No. NHTSA-2026-0727]
3. RIN 2127-AM80

AGENCY:

National Highway Traffic Safety Administration (NHTSA), Department of Transportation (DOT).

ACTION:

Interim final rule; request for comments.

SUMMARY:

This interim final rule amends the seat belt warning requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 208, “Occupant crash protection” in response to petitions for reconsideration of the January 2025 final rule. This interim final rule delays the compliance dates and makes technical clarifications to the regulatory text. NHTSA denies the remainder of the requests. Though these amendments are effective immediately, to benefit from comments interested parties and the public may have, NHTSA requests that any comments be submitted to the docket for this rule. Following the close of the comment period, NHTSA will publish a final rule responding to any comments received and making any appropriate changes to the interim final rule.

( printed page 17145)

DATES:

This interim final rule is effective April 6, 2026. Comments concerning this document are due no later than May 21, 2026. The compliance date of this interim final rule is September 1, 2028, with optional early compliance permitted. Multi-stage manufacturers and alterers have an additional year to comply.

ADDRESSES:

You may submit comments electronically to the docket identified in the heading of this document by visiting the Federal eRulemaking Portal at https://www.regulations.gov. Follow the online instructions for submitting comments.

Alternatively, you can file comments using the following methods:

• Mail or Hand Delivery: Docket Management, U.S. Department of Transportation, 1200 New Jersey Avenue SE, West Building, Suite W58-213, Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except on Federal holidays. To be sure someone is there to help you, please call (202) 366-9826 or (202) 366-9317 before coming.
• Fax: (202) 493-2251. Instructions: All submissions must include the agency name and docket number or Regulatory Information Number (RIN) for this rulemaking. For detailed instructions on submitting comments and additional information on the rulemaking process, see the Public Participation heading of the Supplementary Information section of this document. Note that all comments received will be posted without change to https://www.regulations.gov, including any personal information provided. Please see the Privacy Act heading below.

Docket: For access to the docket to read background documents or comments received, go to https://www.regulations.gov or the street address listed above. Follow the online instructions for accessing the dockets via internet.

Confidential Business Information: If you claim that any of the information in your comment (including any additional documents or attachments) constitutes confidential business information within the meaning of 5 U.S.C. 552(b)(4) or is protected from disclosure pursuant to 18 U.S.C. 1905, please see the detailed instructions given under the Public Participation heading of the SUPPLEMENTARY INFORMATION section of this document.

Privacy Act: Please see the Privacy Act heading under the Regulatory Analyses section of this document.

FOR FURTHER INFORMATION CONTACT:

For non-legal issues, you may contact Ms. Carla Rush, Office of Crashworthiness Standards (Carla.Rush@dot.gov; facsimile: (202) 493-2739). For legal issues, you may contact Mr. John Piazza, Office of Chief Counsel (John.Piazza@dot.gov). You can reach these officials by phone at 202-366-1810. Address: National Highway Traffic Safety Administration, U.S. Department of Transportation, 1200 New Jersey Avenue SE, West Building, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

I. Background

II. Petitions for Reconsideration

III. Response to Petitions

a. Lead Time

b. Front Seat Belt First-Phase Audible Warning Duration Requirement

c. Visibility of Rear Seat Belt Visual Warning in Vehicles With No Driver's Designated Seating Position

d. Front Seat Belt Audible Warning Trigger Requirement

e. Rear Seat Belt Warning System Occupancy Criteria

f. Rear Seat Change-Of-Status Warning Requirement for Two-Door Vehicles

g. Telltales Associated With Multiple Front Outboard Seats

IV. Basis for Issuing an Interim Final Rule Effective Immediately

V. Request for Comment

VI. Rulemaking Analyses and Notices

VII. Public Participation

I. Background

On January 3, 2025, NHTSA published a final rule (90 FR 390) that amended the seat belt warning system provisions in FMVSS No. 208, “Occupant crash protection.” The final rule followed a 2023 Notice of Proposed Rulemaking (NPRM). [1 ] The final rule had two main components. The first required a seat belt warning for the rear seats. The second updated and enhanced the current seat belt warning requirements for the driver's seat belt and extended those requirements to the front outboard passenger seat. The rule completed NHTSA's response to a mandate in the Moving Ahead for Progress in the 21st Century Act (MAP-21) [2 ] that directed NHTSA to initiate a rulemaking to require a seat belt warning for the rear seats in motor vehicles; it also completed NHTSA's action on a rulemaking petition from Public Citizen and Advocates for Highway and Auto Safety for the same rule. The final rule applies (with some exceptions) to passenger cars, trucks, most buses, and multipurpose passenger vehicles (MPVs) with a gross vehicle weight rating (GVWR) of 4,536 kilograms (10,000 pounds) or less.

The final rule established a compliance date for the amendments as follows. Covered vehicles must comply with the front seat belt warning system requirements by September 1, 2026, and the rear seat belt warning system requirements by September 1, 2027, with optional early compliance permitted. Consistent with 49 CFR 571.8(b), multi-stage manufacturers and alterers have an additional year to comply.

II. Petitions for Reconsideration

NHTSA regulations allow any interested person to petition the Administrator for reconsideration of a rule. [3 ] Under NHTSA's regulations, petitions for reconsideration must explain why compliance with the rule is not practicable, is unreasonable, or is not in the public interest. Petitions must be received within 45 days of the publication of the final rule.

NHTSA received petitions for reconsideration of the final rule from IEE Sensing Inc. (IEE); [4 ] the Alliance for Automotive Innovation (Auto Innovators); [5 ] Volkswagen Group of America (Volkswagen); [6 ] and the Autonomous Vehicle Industry Association (AVIA). [7 ] Volkswagen supported Auto Innovators' petition. Auto Innovators also submitted supplemental information to NHTSA. [8 ]

Generally, the issues raised by the petitioners are of two types. Auto Innovators and Volkswagen asked NHTSA to delay the compliance date for the requirements, and all petitioners requested revisions or clarifications of certain aspects of the rule. These requests and NHTSA's responses are discussed below.

III. Response to Petitions

a. Lead time

The final rule established a compliance date of September 1, 2026 for the front seat belt warning system requirements and September 1, 2027 for the rear seat belt warning system requirements, with optional early compliance. Consistent with 49 CFR 571.8(b), multi-stage manufacturers and alterers were given an additional year to comply.

Comments on the NPRM regarding lead time were mixed. Auto Innovators and other industry commenters requested additional lead time. For example, Auto Innovators, Ford, and ( printed page 17146) Honda requested a synchronized two-year phase-in for both the front and rear row seating position requirements that begins three years after publication of the final rule. On the other hand, other commenters requested less lead time. For example, Advocates for Highway and Auto Safety (Advocates) and Public Citizen stated that one year should be sufficient for rear systems, noting that the Insurance Institute for Highway Safety (IIHS) testing has demonstrated that this deadline is achievable and that delaying will cost lives.

Reconsideration Requests

Auto Innovators requested that the agency delay the start date for the front seat belt warning system requirements to September 1, 2027, and delay the start date for the rear seat belt warning system requirements to September 1, 2028. With respect to the requirements for the front seat belts, Auto Innovators stated that implementing the rule will require significant hardware and software changes to support occupant detection, possible modifications to the instrument panel for the visual warnings, and changes to account for the audible warning requirements. It also argued that the increased complexity of the test procedures will require time and resource-intensive design, development, and validation. Auto Innovators cited similar concerns with respect to meeting the rear seat belt reminder system requirements, such as solving design challenges associated with folding or removable seats and developing a change-of-status audible warning. Auto Innovators also commented that implementing changes such as those required by the final rule to vehicles that have already completed development, or are in the late stages of development, is highly disruptive, and that it may not be possible for Tier 1 suppliers to meet the updated timelines. Volkswagen supported Auto Innovators' petition.

In its supplemental submission, Auto Innovators provided additional information based on a survey it conducted of its members to better understand the impact of the final rule based on the current lead time. Based on the survey, it identified that the most significant compliance challenges posed by the final rule stem from the need to either redesign the instrument panel to accommodate the requirements of the rule (for the front and rear seats) or redesign existing seat belt reminder systems that were voluntarily installed. Auto Innovators stated that some manufacturers reported already incurring costs because of the current lead time, but because manufacturers are still in the process of adjusting their production schedules to meet the final rule, it is not possible to assess what the overall cost impact will be. Further, Auto Innovators stated that while cost is a factor, its members were more concerned with the practicability of making late-stage design changes (specifically, about not having enough time to test software for bugs or unintended consequences), and that unpredictable results during validation could require launch delays or even cancellations. Auto Innovators stated that while manufacturers typically require between 24 and 36 months to validate a new software rollout on one model, the final rule allows only 15 months to validate new software on all makes/models, which will be difficult-to-impossible to accomplish. It further stated that “[t]here seems to be strong consensus among our members that delays will happen, but the actual volume, or the models at risk, are unknown until the software/hardware validation is finished.”

Auto Innovators also requested that the agency implement a two-year phase-in of the front seat belt warning requirements if NHTSA does not adopt Auto Innovators' requested changes to those requirements. [9 ] Specifically, Auto Innovators requested a two-year phase-in under which 50 percent of covered vehicles would comply beginning on September 1, 2027, and 100 percent of covered vehicles would comply by September 1, 2028.

Agency Response

On consideration of the petitions and additional information submitted to NHTSA, NHTSA concludes that Auto Innovators' arguments for delaying the compliance dates have merit. In response to Auto Innovators' request to amend the front seat belt visual warning requirements (see Section III.g.), NHTSA is extending the compliance date for the front seat belt warning requirements to 2028. Instead of specifying the phase-in requested by Auto Innovators, NHTSA is unifying the compliance dates for the front and rear requirements, so that full compliance with the front and rear seat belt warning requirements will need to be met by September 1, 2028. Taking into account typical design cycles, the necessary adjustments to existing systems, and the implementation of a rear seat belt warning system in some vehicles, NHTSA concludes the burden on manufacturers is extensive enough to warrant such a delay and unification of the compliance dates.

The change in lead time provides regulatory relief and addresses a potential economic disruption to the light vehicle market based on new information not available at the time that the Final Regulatory Impact Analysis (FRIA) was developed in support of the 2025 final rule.

Based on the information submitted to NHTSA, light vehicle manufacturers are facing challenges in ensuring full compliance with the requirements of the 2025 final rule within the current lead time. The challenges faced by light vehicle manufacturers are based on the time needed to validate their systems, to redesign instrument panels, and to redesign current voluntarily-installed systems to meet the requirements for all models. As a result of these challenges, light vehicle manufacturers who are working towards meeting the requirements of the 2025 final rule within the current lead time would likely incur greater costs than were estimated in the FRIA and still potentially face noncompliance. NHTSA has developed a Regulatory Impact Analysis (RIA) in support of this interim final rule, included in the docket for this rulemaking, that provides an assessment of the benefits and costs associated with the rule. The assessment is based on available data, and NHTSA requests comments on potential costs and benefits not reflected in those estimates.

The RIA takes into account new information that indicates light vehicle manufacturers are facing challenges in ensuring full compliance across their entire fleet under the given lead time. To ensure full compliance within the current lead time, light vehicle manufacturers may incur additional costs associated with conducting validation tests in an expedited manner and potential late-stage design changes. Given any uncertainty in meeting the requirements, vehicle manufacturers are faced with the decision to either move forward in an effort to meet the requirements and take on additional costs or delay the production of that vehicle until they can ensure it would meet the requirements. NHTSA believes that these decisions have already been made for MY2027 and MY2028, which would be produced during the extension in lead time. In addition, as the compliance dates of the 2025 SBWS final rule grow closer, any deviation from those current production plans would become increasingly costly or even infeasible.

Due to limitations, NHTSA is unable to quantify benefits and costs under the baseline and, therefore, is unable to estimate the incremental benefits and ( printed page 17147) costs under the IFR. More specifically, NHTSA is unable to establish which makes and models would face challenges in meeting the requirements, assess the total number of vehicles impacted, how manufacturers would operate in facing those challenges, and the resulting impacts on consumers, safety outcomes, and the light vehicle market as a whole. As a result of these limitations, NHTSA discusses the benefits and costs qualitatively and assesses the overall impacts of this IFR based on the plausible range of outcomes.

For those vehicles that can meet the requirements under the current lead time, with or without additional costs, the extension in lead time would have no impact on benefits or costs. For those vehicles that would not be able to meet the requirements under the current lead time, regardless of cost, the extension in lead time provides regulatory relief that may result in cost savings. These cost savings would result from the case that, in absence of the extension in lead time, manufacturers would continue to dedicate resources and costs towards testing and validating these systems under a timeline that was not feasible.

Overall, the extension in lead time provides enough time for vehicle manufacturers to operate in a manner that ensures that they can achieve compliance with the requirements with potential cost savings. Therefore, on net, the extension in lead time provided by IFR would be beneficial to society.

b. Front Seat Belt First-Phase Audible Warning Duration Requirement

The final rule regulatory text in S7.5(b)(2)(ii) states that the first phase audible warning for the front seats “. . . must continue for 30 seconds, until the seat belt that triggered the warning is in use, until the seat is no longer occupied, or until the second-phase warning activates, whichever comes first.”

Reconsideration Request

Volkswagen noted that this language is different than that used in the rear seat change-of-status warning requirement which specifies that the warning must last “at least 30 seconds.” However, Volkswagen also noted that there were several references in the preamble of the final rule that indicate the first phase audible warning must last for “at least” 30 seconds, suggesting that it was not NHTSA's intent to limit the warning to 30 seconds. Volkswagen therefore requested changing the regulatory text to “at least 30 seconds.”

Agency Response

Volkswagen is correct that it was not NHTSA's intent to limit the front seat belt first-phase audible warning to 30 seconds. This interim final rule revises the regulatory text to clarify this. NHTSA seeks comment on this clarification.

c. Visibility of Rear Seat Belt Visual Warning in Vehicles With No Driver's Designated Seating Position

The final rule requires that the rear seat belt visual warning must be visible from the driver's seat [10 ] and does not include any provisions applicable to vehicles equipped with an Automated Driving System (ADS). The final rule does, however, include visibility requirements for the front seat belt warning specifically tailored to ADS-equipped vehicles. Specifically, the final rule requires that for dual-mode ADS-equipped vehicles that still have a driver's seat, the visual warning for the front outboard passenger seat belt must be visible from the front outboard passenger seat. For ADS vehicles without a driver's seating position, the final rule requires that the visual warning for each outboard designated seating position be visible from each outboard passenger seating position (i.e., the visual warning for the outboard seat on the left must be visible from both the left and right outboard seats, and same for the outboard seat on the right). In the final rule NHTSA stated that the visibility of rear seat belt warnings for ADS-equipped vehicles was outside the scope of the rule and noted that research was underway.

Reconsideration Request

AVIA disagreed that such research is necessary or that rear seat belt warnings for ADS-dedicated vehicles should be out of scope (regardless of seating configuration). AVIA petitioned NHTSA to modify the final rule to require that, in the absence of a driver's designated seating position, all rear outboard visual warnings should be visible to each front outboard seating position.

Agency Response

NHTSA is denying this request. NHTSA continues to believe that the visibility of the rear seat belt warnings for ADS-equipped vehicles is out of scope of the rule, and continues to research this issue to determine the most effective implementation of telltales and warnings for ADS-equipped vehicles. While AVIA's proposed modification would provide consistency in the visual warning requirements for front and rear designated seating positions, we note that the use cases for front row and rear row occupancy in vehicles without a driver's designated seating position may differ from those with a driver's designated seating position and are not yet well-defined. For example, in a rideshare vehicle there may be cases where only the rear seats are occupied, and a visual warning visible to each front outboard seating position may not be visible to the rear seat occupants. Thus, such a warning would be ineffective. Similarly, there may be cases where the vehicle occupants of a rideshare vehicle do not know each other, thus when the front outboard seat occupants are presented visual warnings related to rear seat belt usage, they may not feel compelled to act. Effective implementation of the visual warnings in vehicles with unconventional seating (and other related considerations, such as bi-directional vehicles) would also need to be taken into consideration. NHTSA plans to issue a separate rulemaking document that will focus on telltales and warnings for ADS-equipped vehicles. [11 ]

However, we note that manufacturers of ADS-equipped vehicles, in complying with the front seat belt visual warning requirement for vehicles without a driver's designated seating position (S7.5(b)(1)(iii)) by locating the visual warnings for each front outboard passenger designated seating position such that they are visible from each front outboard passenger designated seating position, may choose to locate the visual warnings for the rear seat designated seating positions in the same location. NHTSA has considered this issue and determined that the final regulatory text would not prohibit such an implementation.

Manufacturers of ADS-equipped vehicles without a driver's designated seating position can petition the agency for an exemption from S7.5(c)(3)(ii), provided that an alternate approach to effective communication of rear seat belt warnings to the rear seat occupants is implemented.

d. Front Seat Belt Audible Warning Trigger Requirement

The final rule requires that the front seat belt first-phase audible warning activate whenever the ignition switch is placed in the “on” or “start” position, “or upon manual activation of the propulsion system, but prior to the vehicle being placed in `possible active ( printed page 17148) driving mode' as defined by FMVSS No. 305,” among other trigger conditions.

Reconsideration Request

Volkswagen requested clarification on whether the option to activate the front seat belt first-phase audible warning not only at ignition but also at activation of the propulsion system applies to internal combustion engine (ICE) vehicles that have been shifted into a reverse or driving gear as well as electric vehicles (EVs).

Agency Response

The final rule requires that the relevant trigger for the first-phase audible warning in ICE vehicles is when the ignition switch is placed in the “on” or “start” position. The proposed regulatory text referred simply to the ignition switch being in the “on” or “start” position. However, commenters pointed out that this did not take EVs into account. NHTSA agreed, and added the language to which VW refers (that the warning activate upon manual activation of the propulsion system, but before the vehicle is placed in “possible active driving mode” as defined by FMVSS No. 305). As we explained in the final rule, our goal in adding this language was to specify a time in the start-up process to begin the start-of-trip warning for EVs that is roughly the same as the time we specified for vehicles with a conventional ignition switch such that the safety benefits for EVs would be the same as for ignition-equipped vehicles. That is, the intent of the language was to specify a trigger for EVs that approximated the trigger for ICE vehicles, not the other way around. Moreover, VW's suggested change would permit the audible warning in an ICE vehicle to be delayed until the vehicle is shifted into gear. As NHTSA explained in both the NPRM [12 ] and final rule, we believe that for ICE vehicles, basing the trigger on the ignition switch is preferable to delaying the warning until the vehicle is placed in gear. With that delay, there could be instances where a driver would pull out onto the road before the warning starts and before passengers have belted.

e. Rear Seat Belt Warning System Occupancy Criteria

The use of occupant detection enables the use of more effective warnings, such as audible alerts. NHTSA recognized in the final rule, however, that occupant detection for the rear seats continues to present technological and cost challenges, so the final rule does not require or necessitate occupant detection to meet the rear seat belt warning system requirements. (Approximately 7 percent of MY 2022 vehicles in the U.S. were equipped with occupant detection in the rear seats.) The final rule requires only a start-of-trip visual warning indicating how many or which rear seat belts are in use and/or not in use; this necessitates a seat belt buckle sensor and associated components, not any occupant detection capabilities. For vehicles that manufacturers equip voluntarily with occupant detection, the final rule specifies that a visual warning is not required for an unoccupied seat.

For testing the seat belt warning with an occupied seat, the final rule specifies (at the option of the manufacturer) either an anthropomorphic test device at least as large as a 49 CFR part 572, subpart N 6-year-old child dummy or a human occupant 21 kg (46.5 lbs.) or more in weight and 114 cm (45 inches) or more in height. [13 ] This differs from Economic Commission for Europe (ECE) Regulation No. 16 (R16), which specifies the use of a fifth percentile female (108 lbs. [50 kg]) or similar weight.

A number of commenters to the NPRM disagreed with specifying a six-year-old child dummy and recommended specifying criteria corresponding to a fifth percentile female. Among other things, they identified technological issues with detecting occupants as small as a six-year-old. They also commented that vehicle models already equipped with rear seat occupant detection were based on detecting a fifth percentile female and argued that if NHTSA specified the use of an occupant corresponding to a six-year-old, manufacturers would be forced to downgrade the rear seat belt warning systems in these vehicles by removing the occupant detection.

NHTSA finalized the use of a six-year-old child dummy because it determined that a system based on a fifth percentile female could result in unbelted child occupants in the rear not benefitting from the seat belt warning. For instance, if a negative-only system [14 ] with occupant detection did not detect an unbelted child smaller than the fifth percentile female seated in a rear seat, the visual warning would not indicate an unbelted child occupant (e.g., for systems with a pictogram that indicates which seat are not in use, the pictogram would likely display something like a “grayed-out” seat to indicate that the system was registering a seat as unoccupied). In this scenario, the driver may not realize that the system is not detecting the unbelted child occupant and may believe the child is restrained when they are not. We noted that this concern is not hypothetical and pointed to an owner's manual alerting the owner that the seat belt system might not detect a child (or small adult) sitting in the seat. We also noted that the fact that the system does not work for some classes of occupants could also lead the driver to be less likely to respond to accurate warnings, and that these shortcomings could also affect consumer acceptance.

NHTSA recognized the technical and cost challenges detection of a six-year-old presents, but noted that the final rule does not require occupant detection. We also suggested that these challenges were not insurmountable. The final rule acknowledged that because the belt use rates for children ages 6 to 10 are already so high, there would be much smaller monetizable benefits for those children. There would be greater benefits for older children, but because NHTSA did not have the data for older children broken out from the data for adults, NHTSA was unable to specifically estimate the benefits for older children as a group. NHTSA acknowledged that specifying the 6-year-old child dummy could lead manufacturers to offer fewer rear seat belt reminder systems with occupant detection. However, we believed that it was important to ensure that vulnerable younger occupants would be covered by the warning.

Reconsideration Request

IEE urged NHTSA to specify criteria corresponding to a fifth percentile female for the purposes of testing the seat belt reminder system with an occupied seat. At the same time, however, IEE appeared to recognize that occupant detection based on a fifth percentile female (together with a start-of-trip audible warning for such occupants that are unbelted) are compatible with the final rule. This is possible because the final rule requires simply a visual warning indicating belt status at vehicle start-up; manufacturers may therefore comply with the final rule by providing a visual warning indicating the status of the rear seat belts—regardless of whether the system detects an occupant at a seat—together with an audible warning for occupants at least as large as a fifth percentile ( printed page 17149) female that the occupant detection system is able to detect. Nevertheless, IEE made a number of arguments in support of its request to specify criteria corresponding to a fifth percentile female.

IEE argued that MAP-21 does not mandate or identify a specific target population for the rear seat belt warning, and that seat belt reminder systems are not a “child safety” technology. IEE also commented that NHTSA did not provide adequate notice and opportunity to comment on the proposal because the final rule interpreted MAP-21 in a way that the NPRM did not; IEE therefore could not take this reasoning into account in its NPRM comments.

IEE also urged NHTSA to harmonize with ECE R16 and worldwide New Car Assessment Program (NCAP) protocols, which use the fifth percentile female occupancy criteria for performance testing purposes. IEE also commented that the European market shows that vehicle manufacturers respond positively to incentives for enhanced rear seat SBR systems and that fitment with occupant detection has increased greatly since Euro NCAP began incentivizing it in 2018. In addition, IEE argued that this would also lead to lower costs and more technological improvement than the final rule. IEE also argued that the restrictive final rule requirements leave almost no room for NCAP to incentivize performance above and beyond the regulatory minimum.

IEE also commented on various technological challenges with detecting smaller occupants, such as variables in the vehicle environment and the need to detect consistently and accurately such small occupants for the purposes of a compliance test while at the same time minimizing false warnings. IEE also commented that while additional in-cabin sensing technologies (e.g., cameras) are installed increasingly for other functionalities, such technologies cannot be considered within the lead time provided by the final rule, but that instead specifying a fifth percentile female would give vehicle manufacturers the opportunity to innovate. IEE also commented that the rule was not practicable with the finalized lead time, and that even if possibly feasible, the efforts to achieve compliance would lead to significant redevelopment costs.

IEE commented that specifying criteria corresponding to a six-year-old would impact negatively the safety of vehicles already available on the market by discouraging vehicle manufacturers from adding voluntarily occupant detection and enhanced features that go beyond the basic compliance option. IEE commented that this would degrade safety because vehicles with occupant detection are able to provide more effective enhanced reminders. IEE also argued that NHTSA provided no evidence to justify safety concerns about vehicles equipped with rear seat belt reminder systems utilizing occupant detection based on a fifth percentile female.

Related to this, IEE argued that the appropriate target population for occupant detection-enabled systems is teens and adults, not small children, because, as noted in the final rule (and FRIA), the belt use rate for children ages 6 to 10 is very high (98 percent), so that the potential benefits for this group is quite small compared to occupants 11 years old and older. IEE argued that most child occupants 11 years old and older would be detected by sensors designed to detect a fifth percentile female.

Accordingly, IEE argued that there would be greater benefits if NHTSA were to specify occupant criteria corresponding to a fifth percentile female for the purposes of testing with a rear seat occupied. Based on a 2012 study, [15 ] IEE estimated that an audio-visual rear seat belt warning is 3.3 times more effective than a visual-only warning to the driver. Based on this effectiveness estimate, IEE estimated the potential benefits of occupant detection given different fitment rates for occupant detection (the percentage of the fleet with such systems). IEE estimated that for occupants 11 years old and older, benefits range from 53 lives saved (with a 20 percent fitment rate) to 114 (with a 100 percent fitment rate). On the other hand, IEE estimated that under the final rule, which requires 100 percent fitment, only 2 lives would be saved for children ages 6 to 10. IEE argued that this showed that the potential loss for adults (by removing occupant detection and enhanced warnings) is significantly higher than the potential gain for children (by imposing 6-year-old detection).

Agency Response

NHTSA is denying IEE's request because the flexibility IEE is requesting is, to a great extent, already permitted by the final rule. To the extent that IEE is requesting additional flexibility that would be enabled by specifying occupancy criteria corresponding to a fifth percentile female, NHTSA is denying the request because NHTSA believes that specifying criteria corresponding to a fifth percentile female would allow a visual start-of-trip warning that would not alert the driver to an unbelted young (small) occupant.

NHTSA agrees, as IEE points out in its petition, that a visual warning that complies with the final rule can be implemented independently of the occupant detection threshold or any occupant detection. Therefore, the final rule need not—and does not—prohibit vehicles from being equipped with an occupant detection system capable of detecting occupants only at least as large as a fifth percentile female (and providing an audible warning for such occupants who are unbelted), as long as the visual warning complies with the final rule when the vehicle is tested for compliance using an occupant as small as a six-year-old dummy.

A manufacturer wishing to equip vehicles with an occupant detection system capable of detecting occupants only at least as large as a fifth percentile female could proceed as follows: The final rule requires a visual warning to the driver at vehicle start-up indicating how many or which rear seat belts are in use and/or not in use, irrespective of the occupancy status of the rear seats. It is therefore possible to comply with this visual warning requirement using only buckle sensors; it does not necessitate occupant detection. As long as the seat belt warning system provides a compliant start-of-trip visual warning that informs the driver of the use status of the rear seat belts, irrespective of occupancy, nothing precludes the manufacturer from also equipping the vehicle with an occupant detection system capable of detecting occupants only as large as a fifth percentile female. Further, there is nothing in the final rule preventing the seat belt warning system from using this occupant detection capability to provide, in addition to the visual warning on vehicle start-up, an audible warning.

So, for example, a manufacturer could equip a vehicle with a full-status system [16 ] with a visual warning indicating the use status of the rear seat belts, and also provide an audible warning if the system detects an unbuckled occupant at least as large as a fifth percentile female. Such a system would be able to pass a compliance test if NHTSA seated a six-year-old dummy, because the final rule requires only a ( printed page 17150) start-of-trip visual warning which is based on buckle status, not occupancy. The rule would require a visual warning that does not depend on occupant size, and so will not leave out young children who should be belted, while at the same time providing manufacturers the flexibility to utilize occupant detection and an audio-visual warning for larger occupants (teens and adults).

However, because an occupant detection system based on a fifth percentile female would not be capable of detecting occupants as small as a six-year-old, the system would not be permitted to take advantage of all the flexibilities the final rule would permit for systems capable of detecting a six-year-old. In particular, the system would not be able to take advantage of the exemption in the final rule from providing a start-of-trip visual warning for an unoccupied seat for systems that are able to determine whether a seat is occupied. (ECE R16 has a similar provision for systems with occupant detection. [17 ]) This enables the warning system to provide more streamlined and informative warnings to the driver. It would allow the seat belt reminder system to function as more of a “true” warning (i.e., providing a warning only if there is an unbuckled occupant). [18 ] These types of warnings might be more effective than the warnings a system without occupant detection is able to provide. However, NHTSA is not aware of any data on whether there is a difference in effectiveness between a “true” warning and an informational warning, and, if there is a difference in effectiveness, the magnitude of this difference. NHTSA has concluded that whatever advantages such warnings could offer for older (larger) occupants, out of concern for younger (smaller) occupants the final rule should not allow it.

NHTSA acknowledges that while the finalized regulatory text permits a rear seat belt warning system that utilizes occupant detection based on a fifth percentile female, the final rule preamble introduced ambiguity on this issue inadvertently. In many instances NHTSA stated accurately that the final rule specified the dummy NHTSA would use in testing compliance. [19 ] However, at other points, NHTSA stated that the final rule specified the minimum size of occupant that an occupant detection system must be able to detect. [20 ] NHTSA is now clarifying that the final rule does not prevent a manufacturer from equipping a vehicle with an occupant detection system capable of detecting occupants only at least as large as a fifth percentile female. Rather, the final rule specifies that for testing purposes NHTSA may seat an occupant as small as the six-year-old dummy and the system must provide a start-of-trip visual warning indicating accurately how many or which rear seat belts are in use and/or not in use.

NHTSA does not have information on whether already-deployed occupant detection systems would comply with the final rule. If they do, no changes would be necessary to comply with the final rule. If not, they will need to be modified. NHTSA is clarifying in this interim final rule, however, that the system would not need to be capable of detecting a six-year-old child dummy; consequently, any modifications would be to the visual warning. Such changes should not be unduly burdensome and are in line with other changes to already-deployed visual warnings that might be necessitated by other parts of the final rule, such as redesigning the visual display and modifying software. The final rule would therefore not necessarily require manufacturers to downgrade significantly vehicle models that are already equipped with occupant detection systems that detect occupants only as small as a fifth percentile female. To the extent that deployed systems do not already comply with the final rule, IEE is correct that NHTSA does not have data on whether such systems have led to consumer confusion or safety issues (i.e., the driver believing that an unrestrained younger child was belted). However, as we discuss here and in the final rule, NHTSA is concerned that this leaves out an entire category of occupants. In the absence of data either way, NHTSA is deciding to specify a six-year-old criterion for testing with a seat occupied to ensure that the driver does not receive a visual warning that could lead her or him to believe erroneously an unbelted child is belted.

The clarification that the final rule does not prevent manufacturers from equipping vehicles with an occupant detection system capable of detecting occupants only at least as large as a fifth percentile female resolves many of the arguments IEE raises in its petition. The final rule therefore allows manufacturers to take advantage of most of the enhanced features provided by systems utilizing occupant detection based on a fifth percentile female. The final rule is also compatible with ECE R16 because a rear seat belt system with an occupant detection system designed to detect reliably occupants as small as a six-year-old will also be able to detect larger occupants. The fact that the final rule is compatible with occupant detection based on a fifth percentile female also addresses IEE's argument concerning the take rate for occupant detection in Europe. With respect to lead time, though systems utilizing occupant detection based on a fifth-percentile female might still need some modifications, this should not necessarily be more burdensome than equipping vehicles with rear seat belt warnings generally and providing a compliant warning, especially with the delayed compliance date.

Turning to IEE's other arguments, NHTSA agrees that MAP-21 does not necessarily require NHTSA to specify an occupant corresponding to a six-year-old child for compliance testing. Among other things, the MAP-21 mandate is subject expressly to § 30111 of the Safety Act, which requires that a safety standard both meet the need for safety and be practicable. In any case, as NHTSA also pointed out in the final rule, the Safety Act gives NHTSA the discretionary authority to issue safety standards to address specific safety needs. NHTSA's decision therefore does not depend on MAP-21 because NHTSA has concluded independently that specifying occupancy criteria corresponding to a six-year-old meets the need for safety and is practicable.

NHTSA does not disagree that there are technological challenges associated with detecting a six-year-old. NHTSA also appreciates IEE's point, in response to NHTSA's observation in the final rule that some vehicle owners' manuals seem to suggest that some rear seat occupant detection systems may be capable of detecting occupants as small as a six-year-old, that there is a difference between detection of a small object at the edge of a system's performance envelope and a system that ( printed page 17151) is able to detect reliably smaller occupants in a pass-fail compliance context. It is for these reasons that the final rule does not require occupant detection.

NHTSA does not agree with IEE that the target population for rear seat belt reminders would be represented adequately by specifying criteria corresponding to a fifth percentile female. There are a couple of reasons for this.

First, NHTSA does not agree with IEE that the target population for rear seat belt reminders is limited to teens and adults and does not or should not include younger (smaller) children. That is, even though NHTSA's regulatory analysis shows that there are fewer monetizable benefits for children ages 6 to 10, NHTSA is not convinced that this group should not get the benefit of a warning. Children 12 years old or younger account for over half of rear seat occupants, [21 ] and many of these children (depending on their height and weight) will (and should) be wearing a seat belt. [22 ]

Second, IEE's request recognizes implicitly that the target population includes some children smaller than a fifth percentile female. IEE stated that “ `low' belt wearing rates are typically an issue for adults and teenagers” [23 ] and that “[t]he 11+ age group is a good approximation of the population covered by sensors designed for a 5% female detection, and most occupants in that group will be detected[.]” [24 ] However, based on weight, specifying criteria corresponding to a fifth-percentile female ((which weighs 108 lbs. [50 kg])) would exclude the following proportions of children by age, each of which weighs less than 108 lbs.: [25 ]

• 92 percent of 11-year-old boys and 90 percent of 11-year-old girls;
• 80 percent of 12-year-old boys and 77 percent of 12-year-old girls;
• 66 percent of 13-year-old boys and 64 percent of 13-year-old girls;
• 42 percent of 14-year-old boys and 49 percent of 14-year-old girls;
• 21 percent of 15-year-old boys and 36 percent of 15-year-old girls;
• 9 percent of 16-year-old boys and 26 percent of 16-year-old girls;
• 4 percent of 17-year-old boys and 20 percent of 17-year-old girls; and
• 2 percent of 18-year-old boys and 16 percent of 18-year-old girls. NHTSA also does not agree with IEE's benefits analysis, for a few reasons.

First, IEE's analysis overstates the benefits because a system that detects occupants only at least as large as a fifth percentile female would not be able to detect a non-trivial proportion of the pre-teens and teens that IEE agrees is part of the target population for a rear seat belt warning system. Many pre-teens and teens are smaller than a fifth percentile female and would not be detected by a rear seat belt reminder system employing an occupant detection system able to detect occupants only as large or larger than a fifth percentile female—and so would not get the benefit of an audio-visual warning.

Second, while NHTSA agrees that a seat belt reminder system that provides an audio-visual warning could be more effective than a visual-only warning, NHTSA is not aware of any persuasive evidence that an audio-visual warning would be three times more effective than a visual-only warning. IEE's effectiveness estimate comes from a 2012 paper that reported the results of an experimental study conducted in Japan on seat belt reminders. That study (which was cited and discussed, but not relied on, in the FRIA) has a number of limitations that make it inappropriate for use in this rulemaking. These limitations stem from the overall design of the study, differences in how seat belt laws are enforced, and seat belt use rates in the U.S. and Japan, among other things. The study was experimental; test subjects were asked to subjectively rate the effectiveness of different types of seat belt reminders. The lack of realism (as opposed to the FRIA, which used observational data) makes the estimates from the study not appropriate for use in this rulemaking. For another thing, the baseline seat belt use rate reported in the study for rear seat occupants in vehicles without a seat belt warning system in Japan was 38 percent. In comparison, the analysis in the FRIA estimated that the baseline rear seat belt use rate without a seat belt warning system in the U.S. was 73.5 percent and 98.2 percent for rear seat occupants ages 6 to 10 and those 11 years and older, respectively. [26 ] These differences between Japan and the U.S. mean that any results do not necessarily translate well to the U.S.

Third and finally, a three-fold increase in effectiveness does not translate into a three-fold increase in benefits. To estimate benefits, IEE multiplied simply the number of fatalities prevented by three, and adjusts this number based on the fitment rate. This oversimplifies the appropriate benefits estimation in a number of ways. For instance, an appropriate benefits estimation requires more than multiplying simply the number of avoided fatalities by the fitment rate. A proper analysis must examine the incremental benefits of the rule: that is, it must account for the baseline fitment rate and the corresponding seat belt use rate to then account for how seat belt use would change and its resulting impact on both non-fatal injuries and fatalities prevented by seat belts. The FRIA presents this analysis in detail. [27 ]

f. Rear Seat Change-Of-Status Warning Requirement for Two-Door Vehicles

The final rule requires an audio-visual rear seat change-of-status warning that activates whenever a fastened rear seat belt is unfastened while the vehicle is in a forward or reverse drive mode and must last for at least 30 seconds or until the seat belt that triggered the warning is re-fastened. This requirement included an exception for the activation of the rear seat change-of-status warning when a rear door is opened (i.e., for a drop-off scenario: a change-of-status warning is not required if a rear passenger unbuckles and exits the vehicle).

Reconsideration Request

Volkswagen sought clarification on this requirement and questioned if the front doors are allowed as a trigger for deactivating the rear change-of-status warning in the case of a vehicle that has rear seating positions and only two front doors (i.e., no rear doors). Volkswagen further requested including a provision for such vehicles to avoid an unnecessary audio-visual warning for a rear seat occupant that has exited the vehicle via a front door, as it has for vehicles that have rear doors.

Agency Response

NHTSA has taken this request into consideration, but is denying the request. The majority of vehicles with rear designated seating positions are ( printed page 17152) equipped with rear doors (approximately 36 percent of vehicles are two-door vehicles, [28 ] but not all of these vehicles have rear designated seating positions). In addition, the requirement that the vehicle must be in a forward or reverse drive mode for a rear seat change-of-status warning to activate aims to mitigate the occurrence of such events. Furthermore, because the change-of-status warning has a required duration that is short, the exposure to the warning in such events would be limited. Lastly, NHTSA determined that specifying simply the use of the front doors would not address sufficiently foreseeable scenarios in which a front door might be opened. For example, if a rear passenger unbuckled their seat belt at the same time that a front passenger exited the vehicle, the change-of-status warning would not be activated for the rear passenger. Therefore, a viable solution would be more complicated than referencing simply the opening of a front door for these vehicles. The additional design changes (e.g., seat track sensor, seat back angle sensor) and cost that would be necessary for a vehicle to comply with a more robust regulatory specification would likely not be justified by the minimal benefit of such efforts (i.e., mitigating consumer annoyance by allowing the deactivation of an already short-duration warning).

However, to further mitigate nuisance activations of the change-of-status warning when a rear passenger has exited the vehicle, NHTSA is revising the requirement to add additional deactivation conditions. Specifically, this interim final rule amends the requirements to permit the warning to deactivate if the vehicle is stopped and no longer in forward or reverse drive mode, or until any rear door is opened, [29 ] or if the system is able to determine that the seating position that triggered the warning is no longer occupied. A behavioral solution to this issue would be for the driver to learn to put the transmission into the park position (or an equivalent mode for an EV) when offloading a rear seat passenger in a two-door vehicle. NHTSA seeks comment on this provision.

g. Telltales Associated With Multiple Front Outboard Seats

The final rule established several requirements for the front seat belt visual warning. Among other things, it required that the visual warning may be continuous or intermittent and must display the identifying symbol or the words specified in table 2 of FMVSS No. 101 (§ 571.101). It also required, in S7.5(b)(1)(v), that a visual warning associated with multiple front outboard seats must identify clearly the seating positions for which the warnings are intended. [30 ] In the preamble of the final rule, NHTSA explained that this requirement did not require a separate telltale for each front seating position nor any particular visual warning design. NHTSA explained that it was giving vehicle manufacturers the flexibility to design their systems such that they can certify in good faith that the visual warning identifies clearly the seating position(s) for which the warning(s) is intended.

Reconsideration Request

Auto Innovators requested that NHTSA modify the requirement that a visual warning associated with multiple front outboard seats must identify the seating position for which the warning was intended. It argued that the requirement is ambiguous and not objectively defined. It also argued that it was unnecessary, because if a visual warning is provided to the driver, the driver should be able to determine if the warning is for them or the front outboard passenger. It argued that the standard should permit the use of a single telltale (i.e., the longstanding telltale specified in FMVSS No. 101) without any additional identifying visual design elements. To accomplish this, Auto Innovators suggested either deleting S7.5(b)(1)(v) in its entirety or modifying it to specify that “the visual warning may include additional visual information.” Auto Innovators pointed out that some existing vehicles already use a single telltale for multiple front seating positions with no additional identifiers and stated consumers are already familiar with this approach. Auto Innovators also commented that, to the extent that NHTSA does not address its comment regarding visual warnings for multiple outboard seats, additional lead time will be needed to implement necessary hardware and software changes to all vehicle model lines. In this scenario, Auto Innovators requested a two-year phase-in beginning on September 1, 2027 (Y1 50%) with full compliance by September 1, 2028 (Y2 100%).

Agency Response

NHTSA agrees that the regulatory language associated with the requirement that a visual warning associated with multiple front outboard seats must “clearly identify” the seating position for which the warning was intended can be specified more clearly. In this interim final rule, NHTSA revises the regulatory text to specify that the warning must use supplementary symbols, words, or abbreviations to indicate the seating positions for which the warnings are intended. As one example, if the manufacturer provides a pictogram, in addition to the FMVSS No. 101 symbol, indicating the buckle status of all seating positions in the vehicle, this pictogram would satisfy this requirement.

However, NHTSA is denying Auto Innovators' suggestion to delete S7.5(b)(1)(v) altogether or make it voluntary. NHTSA's response in the preamble to the final rule described why we are requiring that visual warnings associated with multiple front outboard seats identify the seat for which the warning is intended. NHTSA does not have a basis to conclude that a single telltale with no additional identifiers is familiar to customers, as Auto Innovators did not provide data to support this claim. NHTSA continues to believe that visual warnings associated with multiple front outboard seats must identify the seat for which the warning is intended. This is particularly important when the driver is unbelted, where a visual warning that does not identify which seat the warning is for would not provide useful information to the driver as to whether the front outboard passenger is buckled. Though we are denying this aspect of the petition, NHTSA believes that describing the requirements for visual warnings associated with multiple front outboard seats more clearly (as described above), as well as granting a lead time extension (as described below), will satisfy the request from Auto Innovators.

Removing the requirement would also not align with the level of detail required for the rear seat visual warning, which specifies that the warning must indicate how many or which rear seat belts are in use or not in use. In addition, as noted above, if a manufacturer, in addition to using a single FMVSS No. 101 seat belt telltale symbol for both front seats, uses a pictogram that includes the front seats ( printed page 17153) (perhaps integrated with a pictogram that is used to comply with the new rear seat belt warning requirements) this would comply with the requirement to “use supplementary symbols, words, or abbreviations to indicate the seating positions for which the warnings are intended.”

In its petition for reconsideration, Auto Innovators stated that, if its proposed modifications to the requirements for visual warnings associated with multiple front outboard seats were not addressed by NHTSA, manufacturers would need additional lead time to implement the necessary system changes. In that case, Auto Innovators asked for a two-year phase-in, where 50 percent of vehicles would need to meet the requirements beginning on September 1, 2027 and 100 percent of vehicles would need to meet the requirements beginning on September 1, 2028. As discussed earlier, this interim final rule provides additional lead time such that the front seat belt warning system requirements would become mandatory starting September 1, 2028. As such, the amended lead time would meet the timeline requested by Auto Innovators if the requirements for visual warnings associated with multiple front outboard seats were not amended as requested. Thus, NHTSA is denying Auto Innovators' request for modifications to the requirements for visual warnings associated with multiple front outboard seats, but granting an extension to lead time that encompasses its requested two-year phase-in.

In addition, in reviewing this request from Auto Innovators, NHTSA became aware that the requirements for the rear seat visual warning in S7.5(c)(3)(iv) stated that the rear seat change-of-status warning “may use the same telltale as the start of trip warning.” This language may have been understood to preclude the example described earlier, for telltales associated with multiple front outboard seats, where a manufacturer may choose to display a pictogram in addition to the FMVSS No. 101 telltale. Because the final rule required a telltale for the rear seat change-of-status visual warning, the described pictogram approach would not satisfy the requirement. NHTSA is therefore amending S7.5(c)(3)(iv) to replace “telltale” with “visual warning” to enable this design flexibility.

NHTSA seeks comment on these changes.

IV. Basis for Issuing an Interim Final Rule Effective Immediately

The Administrative Procedure Act (APA) authorizes agencies to issue a rule without notice and comment, and to make a rule effective sooner than 30 days after its publication, if the agency finds good cause for doing so and provides an explanation in the preamble. Similarly, while the National Traffic and Motor Vehicle Safety Act (Safety Act) [31 ] generally requires that a motor vehicle safety standard may not become effective sooner than the 180th day after the standard is prescribed, it too permits NHTSA to establish an earlier effective date if there is good cause to do so. As we explain below, NHTSA has concluded that there is good cause to issue this interim final rule without notice and comment and to make it effective immediately.

Good Cause Justification Under the APA for Waiving Prior Notice and Opportunity for Comment

The APA permits an agency to issue a rule without prior notice and opportunity for comment “when the agency for good cause finds (and incorporates the finding and a brief statement of reasons therefor in the rules issued) that notice and public procedure thereon are impracticable, unnecessary, or contrary to the public interest.” [32 ] Impracticable “means a situation in which the due and required execution of the agency functions would be unavoidably prevented by its undertaking public rule-making proceedings.” [33 ] Unnecessary refers to “those situations in which the administrative rule is a routine determination, insignificant in nature and impact, and inconsequential to the industry and to the public.” [34 ] The public interest element of the good cause exception is properly invoked when “the timing and disclosure requirements of the usual procedures would defeat the purpose of the proposal[.]” [35 ] “The question is not whether dispensing with notice and comment would be contrary to the public interest, but whether providing notice and comment would be contrary to the public interest.” [36 ] Providing notice and comment would be impracticable and contrary to the public interest in the specific circumstances of this interim final rule for several reasons.

First, providing prior notice and opportunity for comment would mean that the final rule would be published too late for manufacturers to utilize the extra lead time afforded by this rule. As noted earlier, based on recent information Auto Innovators has submitted to NHTSA, vehicle manufacturers are experiencing design and production challenges such that they may not be able to ensure full compliance of all covered vehicles within the current lead time. Manufacturers, absent this final rule, are designing and planning production for their vehicles based on the fact that the new front seat belt warning requirements become obligatory on September 1, 2026. Production planning (tooling, supply chains, etc.) necessitates that vehicle designs and concomitant production plans be established well before September 1 for production to take place on and after September 1. Therefore, the delay in lead time implemented by this final rule (which NHTSA believes is necessary for the reasons provided in Section III.a,) would likely come too late for at least some vehicle models were NHTSA to provide for notice and comment; by the time NHTSA were to publish a final rule, manufacturers may have already decided to pause production of some vehicle models due to an inability to fully validate rule-compliant front seat belt systems in time for model year 2027. Accordingly, if this final rule is not published sufficiently in advance of September 1, manufacturers would likely have to delay or even cancel production of vehicle models that they had not yet been able to bring into compliance. Any lapses or delays in production can adversely affect manufacturer revenue, operations, and supply chains, and, if the lapse is long enough, could cause delays or even cancellations of model year launches. This could even include models that currently have provided voluntarily rear or front passenger SBRSs that, while not meeting all of the new requirements, do provide safety benefits. This would affect not only vehicle manufacturers and suppliers, but also consumers, who would enjoy fewer choices in the vehicle market; additional costs caused by the delay might also be passed onto consumers.

Second, NHTSA believes it is reasonable to conclude that there is a non-trivial risk that such launch delays or cancellations would occur and that these would not be isolated occurrences. The new seat belt warning requirements apply to a large majority of the new vehicle fleet. Auto Innovators recently ( printed page 17154) surveyed its members to “understand the impact of the rule based on the current lead time.” [37 ] It stated that “[t]here seems to be strong consensus among our members” that launch delays or even cancellations would occur, though “the actual volume, or the models at risk, are unknown” until vehicle validation is complete. [38 ] Therefore, while NHTSA does not have complete information on this issue and some uncertainty necessarily exists, NHTSA finds that the risk of non-trivial disruption is sufficiently likely to justify waiving notice and comment.

Other factors also support NHTSA's conclusion that there is good cause to waive notice and comment in these particular circumstances. First, this interim final rule is limited in scope. The rule responds to petitions for reconsideration of the January 2025 final rule. NHTSA received a limited number of petitions on a narrow range of topics, most of which concerned relatively minor technical issues and requests for clarification. This interim final rule does not remove or significantly alter any of the requirements in the January 2025 final rule. The major substantive request that NHTSA received, and the change that this interim final rule makes, is to grant vehicle and equipment manufacturers' request for more lead time. However, even this change to the January 2025 final rule is of relatively limited scope and duration. This interim final rule simply provides an additional year of lead time for the rear seat belt requirements and an additional two years for the front seat belt requirements for manufacturers to produce vehicles that comply with the new requirements. Importantly, we do not expect this interim final rule to lead to any decrease in vehicle safety compared to if we did not issue this interim final rule. In addition, the amendments this interim final rule makes are within the scope of the September 2023 NPRM that the public initially commented on, so that, to a large extent, the public has already had the opportunity to comment, and NHTSA has considered those comments in issuing this interim final rule. Finally, NHTSA has no reason to believe vehicle manufacturers have not made a good faith effort to bring vehicles into compliance with the new requirements in a timely fashion; the fact that this is an issue being faced across the entire industry—as opposed to one or two manufacturers—supports this belief. Providing notice and an opportunity to comment prior to the rule taking effect would therefore be contrary to the public interest and defeat one of the purposes of this interim final rule, which is to provide manufacturers with more lead time to prevent any disruptions to the market. NHTSA therefore believes that the public interest would be best served by foregoing notice and comment in this unusual situation. [39 ]

Good Cause Justification Under the APA and Safety Act for an Immediate Effective Date

This interim final rule is effective immediately. While the APA generally requires that the effective date be no sooner than 30 days after the publication date, the APA permits agencies to make rules effective sooner than this for, among other things, “good cause found and published with the rule” [40 ] and rules which grant or recognize an exemption or relieve a restriction. [41 ] Similarly, while the Safety Act generally requires that a motor vehicle safety standard may not become effective sooner than the 180th day after the standard is issued, it too permits an earlier effective date if the Secretary (NHTSA by delegation) determines there is good cause and it is in the public interest. [42 ] For the reasons discussed above, NHTSA finds there is good cause, and it is in the public interest, for this interim final rule to be effective immediately. In addition, to the extent that this interim final rule relieves a restriction (in that it delays the compliance date), this rule is exempt from the APA's effective date delay requirements on that basis as well.

V. Request for Comment

As explained above, the Administrative Procedure Act authorizes NHTSA to issue this interim final rule without prior notice or opportunity for public comment. As an interim final rule, this regulation is in effect and binding upon its effective date. No further regulatory action by NHTSA is necessary to make this rule effective. However, to benefit from comments that interested parties and the public may have, NHTSA is requesting that any comments be submitted to the docket for this notice. NHTSA is providing an opportunity for comment on this interim final rule for 45 days after this action's publication date. Comments received in response to this notice will be considered by the agency. Following the close of the comment period, the agency will publish a final rule responding to the comments and making any necessary changes to the provisions of this interim final rule.

VI. Rulemaking Analyses and Notices

Executive Orders 12866 and 14192

NHTSA has considered the impact of this interim final rule under Executive Order 12866 and Executive Order 14192. NHTSA has considered the costs and benefits of the rule under the principles of these executive orders. Please refer to Section III.a, Lead time and the docketed Regulatory Impact Analysis, for this discussion. The Office of Management and Budget has determined that the interim final rule is a significant regulatory action as defined in section 3(f)(1) of E.O. 12866 and reviewed the rule pursuant to E.O. 12866. This interim final rule is an E.O. 14192 deregulatory action.

Promoting International Regulatory Cooperation

The policy statement in section 1 of Executive Order 13609 provides that the regulatory approaches taken by foreign governments may differ from those taken by the United States to address similar issues, and that in some cases the differences between them might not be necessary and might impair the ability of American businesses to export and compete internationally. It further recognizes that in meeting shared challenges involving health, safety, and other issues, international regulatory cooperation can identify approaches that are at least as protective as those that are or would be adopted in the absence of such cooperation and can reduce, eliminate, or prevent unnecessary differences in regulatory requirements.

In addition, section 24211 of the Infrastructure, Investment, and Jobs Act, Global Harmonization, provides that ( printed page 17155) DOT “shall cooperate, to the maximum extent practicable, with foreign governments, nongovernmental stakeholder groups, the motor vehicle industry, and consumer groups with respect to global harmonization of vehicle regulations as a means for improving motor vehicle safety.” [43 ] As discussed in the September 2023 NPRM and the January 2025 final rule, there are foreign regulations for seat belt reminder requirements.

As discussed in the January 2025 Final Rule, this interim final rule harmonizes with ECE R16, Euro NCAP, and the IIHS protocol as much as possible, but deviates where NHTSA determined deviation was justified with respect to the Safety Act criteria (need for safety, objectivity, and practicability). In general, NHTSA determined that though this rule deviates from these requirements or protocols in some ways, it is not incompatible with them, so that it is possible to design a seat belt reminder system that complies with both this rule and protocols such as R16. The updates included in this interim final rule are intended to further improve compatibility with international standards. Thus, the requirements in this interim final rule are consistent with these international programs and complement those international efforts to increase seat belt use by all vehicle occupants.

Regulatory Flexibility Act

Under the Regulatory Flexibility Act (RFA) (5 U.S.C. 601-612) (as amended by the Small Business Regulatory Enforcement Fairness Act (SBREFA) of 1996; 5 U.S.C. 601 et seq.), where a proposed rule must be published for comment by 5 U.S.C. 553 or any other law, agencies must prepare and make available for public comment a regulatory flexibility analysis that describes the effect of the rule on small entities (i.e., small businesses, small organizations, and small government jurisdictions). No regulatory flexibility analysis is required, however, if the head of an agency or an appropriate designee certifies that the rule will not have a significant economic impact on a substantial number of small entities. Because NHTSA was not required by law to publish a proposed rule, the analytical requirements of the RFA do not apply.

NHTSA has nonetheless analyzed the economic impacts of this rule to determine whether the rule would have a significant economic impact on a substantial number of small entities.

Under the Small Business Administration's size standards regulations used to define small businesses, manufacturers of the vehicles covered by this rule would fall under North American Industry Classification System (NAICS) No. 336211, Automobile Manufacturing, which has a size standard of 1,000 employees or fewer.

NHTSA estimates that there are twelve light vehicle manufacturers in the U.S. with 1,000 employees or fewer. As noted in Section 11.1 of the final regulatory impact analysis, the estimated annual vehicle sales for these manufacturers is less than 100 vehicles with a sales price range of $65,900 to $1,600,000. There are several hundred second-stage or final-stage manufacturers and alterers that could be impacted by this rule, some of which may be considered small. Though this analysis is unable to estimate how many small entities may be impacted by the rule, the rule would either have no impact or generate cost savings for those entities.

The delay in the compliance date would reduce the burden on small entities by providing more time to comply with the new requirements. Revising the regulatory text to clarify that it was not NHTSA's intent to limit the front seat belt first-phase audible warning to 30 seconds also provides manufacturers with more flexibility in designing the system. NHTSA's clarification that the final rule requires that the relevant trigger for the first-phase audible warning in ICE vehicles is when the ignition switch is placed in the “on” or “start” position, and not when the vehicle is in gear, is not a burden on small manufacturers because this mirrors the trigger for the longstanding requirements for the driver's seat belt warning. Amending the rule to specify that the front seat belt visual warning must use supplementary symbols, words, or abbreviations to indicate the seating positions for which the warnings are intended would not have a significant impact because the change merely clarifies the existing regulatory text.

Therefore, NHTSA has concluded that the rule would not have a significant economic impact on a substantial number of small entities.

Unfunded Mandates Reform Act

The Unfunded Mandates Reform Act of 1995 (2 U.S.C. 1531-1538) (UMRA) requires Federal agencies to assess the effects of regulatory actions that may result in the expenditure by a State, local, or Tribal government, in the aggregate, or by the private sector of $206 million (the value equivalent of $100 million in 1995, adjusted for inflation to 2025) or more in any 1 year. This rule does not contain Federal mandates (under the regulatory provisions of Title II of the UMRA) for State, local and Tribal governments, or the private sector of $206 million or more in any one year. Thus, the analytical requirements of the UMRA do not apply to this action.

Executive Order 13175

Executive Order 13175 requires Federal agencies to consult and coordinate with Tribes on a government-to-government basis on policies that have Tribal implications, including regulations, legislative comments or proposed legislation, and other policy statements or actions that have substantial direct effects on one or more Indian Tribes, on the relationship between the Federal Government and Indian Tribes, or on the distribution of power and responsibilities between the Federal Government and Indian Tribes. NHTSA has assessed the impact of this interim final rule on Indian tribes and determined that this rule would not have tribal implications that require consultation under Executive Order 13175.

Paperwork Reduction Act

In accordance with the Paperwork Reduction Act of 1995 (PRA) (44 U.S.C. 3501-3520), an agency may not conduct or sponsor, and a person is not required to respond to, a collection of information, unless the collection displays a currently valid Office of Management and Budget (OMB) control number. This rule does not impose any additional information collection requirements requiring OMB approval under the PRA.

E-Government Act Compliance

NHTSA is committed to complying with the E-Government Act, 2002 to promote the use of the internet and other information technologies to provide increased opportunities for citizen access to Government information and services, and for other purposes. The E-Government Act of 2002 (Pub. L. 107-347, sec. 208, 116 Stat. 2899, 2921, Dec. 17, 2002), requires Federal agencies to conduct a privacy impact assessment for new or substantially changed technology that collects, maintains, or disseminates information in an identifiable form. No new or substantially changed technology would collect, maintain, or disseminate information as a result of this rule. Accordingly, NHTSA has not conducted a privacy impact assessment. ( printed page 17156)

Executive Order 13132; Federalism Summary Impact Statement

NHTSA has examined this rule pursuant to Executive Order 13132 (64 FR 43255; Aug. 10, 1999) and concluded that no additional consultation with States, local governments, or their representatives is mandated beyond the rulemaking process. The agency has concluded that the rule does not have sufficient federalism implications to warrant consultation with State and local officials or the preparation of a federalism summary impact statement. The rule does not have “substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.” NHTSA rules can have preemptive effect in two ways. First, the National Traffic and Motor Vehicle Safety Act contains an express preemption provision: When a motor vehicle safety standard is in effect under this chapter, a State or a political subdivision of a State may prescribe or continue in effect a standard applicable to the same aspect of performance of a motor vehicle or motor vehicle equipment only if the standard is identical to the standard prescribed under this chapter. 49 U.S.C. 30103(b)(1). It is this statutory command by Congress that preempts any non-identical State legislative and administrative law address the same aspect of performance.

The express preemption provision described above is subject to a savings clause under which “[c]compliance with a motor vehicle safety standard prescribed under this chapter does not exempt a person from liability at common law.” 49 U.S.C. 30103(e). Pursuant to this provision, State common law tort causes of action against motor vehicle manufacturers that might otherwise be preempted by the express preemption provision are generally preserved. However, the Supreme Court has recognized the possibility, in some instances, of implied preemption of State common law tort causes of action by virtue of NHTSA's rules—even if not expressly preempted.

This second way that NHTSA rules can preempt is dependent upon the existence of an actual conflict between an FMVSS and the higher standard that would effectively be imposed on motor vehicle manufacturers if someone obtained a State common law tort judgment against the manufacturer—notwithstanding the manufacturer's compliance with the NHTSA standard. Because most NHTSA standards established by an FMVSS are minimum standards, a State common law tort cause of action that seeks to impose a higher standard on motor vehicle manufacturers will generally not be preempted. However, if and when such a conflict does exist—for example, when the standard at issue is both a minimum and a maximum standard—the State common law tort cause of action is preempted impliedly. See Geier v. American Honda Motor Co., 529 U.S. 861 (2000).

Pursuant to Executive Order 13132, NHTSA has considered whether this rule could or should preempt State common law causes of action. The agency's ability to announce its conclusion regarding the preemptive effect of one of its rules reduces the likelihood that preemption will be an issue in any subsequent tort litigation.

To this end, the agency has examined the nature (e.g., the language and structure of the regulatory text) and objectives of this rule and does not foresee any potential State requirements that might conflict with it. NHTSA does not intend that this rule preempt state tort law that would effectively impose a higher standard on motor vehicle manufacturers than that established by this rule. Establishment of a higher standard by means of State tort law would not conflict with the standards in this rule. Without any conflict, there could not be any implied preemption of a State common law tort cause of action.

National Environmental Policy Act

The Department has analyzed the environmental impacts of this rule pursuant to the National Environmental Policy Act of 1969 (NEPA) (42 U.S.C. 4321 et seq.). Pursuant to 49 CFR 1.81, the Secretary has delegated the “functions” under NEPA to the Administrators “as they relate to the matters within the primary responsibility of each Operating Administration.” NHTSA has determined that this rule is categorically excluded pursuant to 23 CFR 771.118(c)(4). Categorical exclusions are actions identified in an agency's NEPA procedures that do not normally have a significant impact on the environment and therefore do not require either an environmental assessment (EA) or environmental impact statement (EIS). 44 This rulemaking, which responds to petitions for consideration on NHTSA's final seat belt reminder systems rule issued in January 2025, is categorically excluded pursuant to 23 CFR 771.118(c)(4): “Planning and administrative activities that do not involve or lead directly to construction, such as: Training, technical assistance and research; promulgation of rules, regulations, directives, or program guidance; approval of project concepts; engineering; and operating assistance to transit authorities to continue existing service or increase service to meet routine demand.” NHTSA does not anticipate any environmental impacts, and there are no extraordinary circumstances present in connection with this rulemaking.

Executive Order 12988 (Civil Justice Reform)

With respect to the review of the promulgation of a new regulation, section 3(b) of Executive Order 12988, “Civil Justice Reform” (61 FR 4729, February 7, 1996) requires that Executive agencies make every reasonable effort to ensure that the regulation: (1) specifies clearly the preemptive effect; (2) specifies clearly the effect on existing Federal law or regulation; (3) provides a clear legal standard for affected conduct, while promoting simplification and burden reduction; (4) specifies clearly the retroactive effect, if any; (5) defines key terms adequately; and (6) addresses other important issues affecting clarity and general draftsmanship under any guidelines issued by the Attorney General. This document is consistent with that requirement.

NHTSA has reviewed this rulemaking and determined that this rulemaking action conforms to the applicable standards in sections 3(a) and 3(b)(2) of E.O. 12988, Civil Justice Reform. The issue of preemption is discussed above in connection with E.O. 13132. NHTSA notes further that there is no requirement that individuals submit a petition for reconsideration or pursue other administrative proceeding before they may file suit in court.

National Technology Transfer and Advancement Act

Under the National Technology Transfer and Advancement Act of 1995 (NTTAA) (Pub. L. 104-113), “all Federal agencies and departments shall use technical standards that are developed or adopted by voluntary consensus standards bodies, using such technical standards as a means to carry out policy objectives or activities determined by the agencies and departments.” Voluntary consensus standards are technical standards (e.g., materials specifications, test methods, sampling procedures, and business practices) that are developed or adopted by voluntary consensus standards bodies, such as SAE (formerly, the Society of Automotive Engineers). The NTTAA ( printed page 17157) directs this agency to provide Congress, through OMB, explanations when the agency decides not to use available and applicable voluntary consensus standards. NHTSA is not aware of any voluntary standards that exist regarding the seat belt warnings in this rule.

Plain Language

Executive Order 12866 and E.O. 13563 require each agency to write all rules in plain language. Application of the principles of plain language includes consideration of the following questions:

• Have we organized the material to suit the public's needs?
• Are the requirements in the rule stated clearly?
• Does the rule contain technical language or jargon that is not clear?
• Would a different format (grouping and order of sections, use of headings, paragraphing) make the rule easier to understand?
• Would more (but shorter) sections be better?
• Could we improve clarity by adding tables, lists, or diagrams?
• What else could we do to make the rule easier to understand? NHTSA has considered these questions and attempted to use plain language in writing this rule. Please inform the agency if you can suggest how NHTSA can improve its use of plain language.

Regulation Identifier Number (RIN)

The Department of Transportation assigns a regulation identifier number (RIN) to each regulatory action listed in the Unified Agenda of Federal Regulations. The Regulatory Information Service Center publishes the Unified Agenda in April and October of each year. You may use the RIN contained in the heading at the beginning of this document to find this action in the Unified Agenda.

Privacy Act

In accordance with 5 U.S.C. 553(c), DOT solicits comments from the public to better inform its rulemaking process. DOT posts these comments, without edit, to www.regulations.gov, as described in the system of records notice, DOT/ALL-14 FDMS, accessible through www.dot.gov/​privacy. To facilitate comment tracking and response, we encourage commenters to provide their name, or the name of their organization; however, submission of names is completely optional. Anyone is able to search the electronic form of all comments received into any of our dockets by the name of the individual submitting the comment (or signing the comment, if submitted on behalf of an association, business, labor union, etc.). For information on DOT's compliance with the Privacy Act, please visit https://www.transportation.gov/​privacy.

Congressional Review Act

As required by 5 U.S.C. 801, NHTSA will submit to Congress a report regarding the issuance of this interim final rule prior to the effective date set forth at the outset of this interim final rule. The report will state that it has been determined that this interim final rule is not a “major rule” as defined by 5 U.S.C. 804(2).

VII. Public Participation

How do I prepare and submit comments?

Your comments must be written and in English. To ensure that your comments are filed correctly in the Docket, please include the docket number indicated in this document in your comments.

Your comments must not be more than 15 pages long. (49 CFR 553.21). We established this limit to encourage you to write your primary comments in a concise fashion. However, you may attach necessary additional documents to your comments. There is no limit on the length of the attachments.

If you are submitting comments electronically as a PDF (Adobe) file, NHTSA asks that the documents be submitted using the Optical Character Recognition (OCR) process, thus allowing NHTSA to search and copy certain portions of your submissions.

Please note that pursuant to the Data Quality Act, for substantive data to be relied upon and used by the agency, it must meet the information quality standards set forth in the OMB and DOT Data Quality Act guidelines. Accordingly, we encourage you to consult the guidelines in preparing your comments. OMB's guidelines may be accessed at https://www.transportation.gov/​regulations/​dot-information-dissemination-quality-guidelines.

How can I be sure that my comments were received?

If you wish the Docket to notify you upon its receipt of your comments, enclose a self-addressed, stamped postcard in the envelope containing your comments. Upon receiving your comments, the Docket will return the postcard by mail.

How do I submit confidential business information?

You should submit a redacted “public version” of your comment (including redacted versions of any additional documents or attachments) to the docket using any of the methods identified under ADDRESSES. This “public version” of your comment should contain only the portions for which no claim of confidential treatment is made and from which those portions for which confidential treatment is claimed has been redacted. See below for further instructions on how to do this.

You also need to submit a request for confidential treatment directly to the Office of Chief Counsel. Requests for confidential treatment are governed by 49 CFR part 512. Your request must set forth the information specified in part 512. This includes the materials for which confidentiality is being requested (as explained in more detail below); supporting information, pursuant to § 512.8; and a certificate, pursuant to § 512.4(b) and part 512, appendix A.

You are required to submit to the Office of Chief Counsel one unredacted “confidential version” of the information for which you are seeking confidential treatment. Pursuant to § 512.6, the words “ENTIRE PAGE CONFIDENTIAL BUSINESS INFORMATION” or “CONFIDENTIAL BUSINESS INFORMATION CONTAINED WITHIN BRACKETS” (as applicable) must appear at the top of each page containing information claimed to be confidential. In the latter situation, where not all information on the page is claimed to be confidential, identify each item of information for which confidentiality is requested within brackets: “[ ].”

You are also required to submit to the Office of Chief Counsel one redacted “public version” of the information for which you are seeking confidential treatment. Pursuant to § 512.5(a)(2), the redacted “public version” should include redactions of any information for which you are seeking confidential treatment (i.e., the only information that should be unredacted is information for which you are not seeking confidential treatment).

NHTSA is currently treating electronic submission as an acceptable method for submitting confidential business information to the agency under part 512. Please do not send a hardcopy of a request for confidential treatment to NHTSA's headquarters. The request should be sent to Dan Rabinovitz in the Office of the Chief Counsel at Daniel.Rabinovitz@dot.gov. You may either submit your request via email or request a secure file transfer link. Manufacturers or any companies that already have a Confidential Business Information (CBI) Portal account or an Enterprise Account with ( printed page 17158) NHTSA should use the CBI Portal for their submission. If you submit a CBI request, please also email a courtesy copy of the request to John Piazza at John.Piazza@dot.gov.

Will the agency consider late comments?

We will consider all comments received before the close of business on the comment closing date indicated above under DATES. To the extent possible, we will also consider comments that the docket receives after that date. If the docket receives a comment too late for us to consider in developing a final rule (assuming that one is issued), we will consider that comment as an informal suggestion for future rulemaking action.

How can I read the comments submitted by other people?

You may read the comments received by the docket at the address given above under ADDRESSES. The hours of the docket are indicated above in the same location. You may also see the comments on the internet. To read the comments on the internet, go to https://www.regulations.gov. Follow the online instructions for accessing the dockets.

Please note that even after the comment closing date, we will continue to file relevant information in the docket as it becomes available. Further, some people may submit late comments. Accordingly, we recommend that you periodically check the Docket for new material. You can arrange with the docket to be notified when others file comments in the docket. See www.regulations.gov for more information.

List of Subjects in 49 CFR Part 571

• Imports
• Motor vehicle safety
• Motor vehicles In consideration of the foregoing, NHTSA amends 49 CFR part 571 as set forth below.

PART 571—FEDERAL MOTOR VEHICLE SAFETY STANDARDS

1. The authority citation for part 571 continues to read as follows:

Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95.

1. Amend § 571.208 by:

a. Revising paragraphs S4.1.5.7 and S4.1.5.7.1;

b. Adding paragraph S4.1.5.7.2;

c. Removing paragraphs S4.1.5.8 and S4.1.5.8.1;

d. Revising paragraphs S4.2.8 and S4.2.8.1;

e. Adding paragraph S4.2.8.2;

f. Removing paragraphs S4.2.9 and S4.2.9.1;

g. Revising paragraphs S4.4.3.4 and S4.4.3.4.1;

h. Adding paragraph S4.4.3.4.2;

i. Removing paragraphs S4.4.3.5 and S4.4.3.5.1; and

j. Revising paragraphs S7.5 introductory text, S7.5(b)(1)(v), S7.5(b)(2)(ii), S7.5(c)(2), and S7.5(c)(3)(iv).

The revisions and additions read as follows:

§ 571.208 Standard No. 208; Occupant crash protection. * * * * * S4.1.5.7. Seat belt warnings for passenger cars manufactured on or after September 1, 2028.

S4.1.5.7.1 Any front outboard designated seating position and any front inboard designated seating position for which a seat belt warning is required in S4.1.5.6 shall comply with S7.5 of this standard.

S4.1.5.7.2. All rear designated seating positions, except in law enforcement vehicles, shall comply with S7.5 of this standard.

• * * * * S4.2.8 Seat belt warnings for trucks and multipurpose passenger vehicles manufactured on or after September 1, 2028 with a GVWR of 4,536 kg (10,000 lb) or less.

S4.2.8.1. Any front outboard designated seating position certified to a compliance option requiring a seat belt and any front inboard designated seating position for which a seat belt warning is required by S4.2.6.4 shall comply with S7.5 of this standard.

S4.2.8.2. All rear designated seating positions certified to a compliance option requiring a seat belt, except for ambulances, as defined by FMVSS No. 201 (§ 571.201), and law enforcement vehicles, shall comply with S7.5 of this standard.

• * * * * S4.4.3.4 Seat belt warnings for buses manufactured on or after September 1, 2028 with a GVWR of 4,536 kg (10,000 lb) or less.

S4.4.3.4.1 All front outboard designated seating positions and any front inboard designated seating position for which a seat belt warning is required by S4.2.6.4 shall comply with S7.5 of this standard.

S4.4.3.4.2 All rear designated seating positions certified to a compliance option requiring a seat belt, except for school buses and law enforcement vehicles, shall comply with S7.5 of this standard.

• • * * * S7.5 Seat belt warning systems for vehicles manufactured on or after September 1, 2028 provided in accordance with the requirements S4.1.5.7, S4.2.8, and S4.4.3.4 of this standard.
• • * * * (b) * * *

(1) * * *

(v) For a visual warning associated with multiple front outboard seats, the visual warning must use supplementary symbols, words, or abbreviations to indicate the seating positions for which the warnings are intended.

• * * * * (2) * * *

(ii) The audible warning must continue for at least 30 seconds, until the seat belt that triggered the warning is in use, until the seat is no longer occupied, or until the second-phase warning activates. The audible warning may be paused during the activation of another audible safety warning that is designed to alert the driver to take immediate action, but the seat belt audible warning must be resumed for the remainder of the required duration after the other audible warning deactivates.

• * * * * (c) * * *

(2) Change-of-status warning. An audio-visual warning indicating how many or which rear seat belts have undergone a change of status from in use to not in use must activate when the status of any rear seat belt changes from in use to not in use and the vehicle is in either forward or reverse drive mode, unless any rear door is open. The warning must continue for at least 30 seconds, until the seat belt that triggered the warning is in use, until the vehicle is stopped and no longer in forward or reverse drive mode, or until any rear door is opened. The warning may deactivate if the system is able to determine that the number of seat belts in use is restored and all the doors remained closed, or if the system is able to determine that the seating position that triggered the warning is no longer occupied.

(3) * * *

(iv) The change-of-status warning may use the same visual warning as the start of trip warning, provided that the color of an illuminated symbol or number , used to indicate to the driver how many or which rear seat belts have undergone a change of status from in use to not in use is red.

• * * * * ( printed page 17159) Issued under authority delegated in 49 CFR 1.95.

Jonathan Morrison,

Administrator.

Footnotes

1. 88 FR 61674 (Sept. 7, 2023).

Back to Citation 2. Public Law 112-141 (2012).

Back to Citation 3. 49 CFR 553.35.

Back to Citation 4.

                     Docket No. NHTSA-2024-0071-0007.

Back to Citation 5.

                     Docket No. NHTSA-2024-0071-0006.

Back to Citation 6.

                     Docket No. NHTSA-2024-0071-0004.

Back to Citation 7.

                     Docket No. NHTSA-2024-0071-0005.

Back to Citation 8.

                     Docket No. NHTSA-2024-0071-0008.

Back to Citation 9.

                     Those requested changes are discussed in Section III.g.

Back to Citation 10.

                     S7.5(c)(3)(ii).

Back to Citation 11. https://www.reginfo.gov/​public/​do/​eAgendaViewRule?​pubId=​202410&​RIN=​2127-AM07.

Back to Citation 12. 88 FR 61674 (Sept. 7, 2023).

Back to Citation 13.

                     These are the bottom of the ranges specified in FMVSS No. 208 S29.1(e) for the weight and height of a human child who may be used in certain of the advanced air bag testing in place of the six-year-old child dummy. The child 6-year-old dummy weighs approximately 24 kg (53 lb).

Back to Citation 14.

                     A negative-only system indicates how many or which rear seat belts are not in use. A negative-only system with occupant detection indicates how many or which of the occupied seats have seat belts which are not in use.

Back to Citation 15.

                     M. Akamatsu, et al “Assessment Method of Effectiveness of Passenger Seat Belt Reminder,” SAE 2012-01-0050 (2012).

Back to Citation 16.

                     A full-status system indicates how many or which rear seat belts are in use and how many or which rear seat belts are not in use. A full-status system with occupant detection indicates, for the occupied rear seats, how many or which rear seat belts are in use and how many or which rear seat belts are not in use.

Back to Citation 17.

                     The revised final rule similarly permits the rear seat belt change-of-status warning to deactivate if the seat with the unfastened belt is no longer occupied (see Section III.f.).

Back to Citation 18.

                     A reminder system utilizing occupant detection based on a fifth percentile female would not be permitted to offer such features because if NHTSA tested the system with a six-year-old dummy in one of the rear seats, the system would not comply with the start-of-trip visual warning requirements (it would classify incorrectly the seat as unoccupied, and therefore not provide a visual warning for it).

Back to Citation 19. See, e.g. id. at 410 (“After considering the comments, NHTSA has decided to adopt the proposal to use (at the option of the manufacturer) either a anthropomorphic test device at least as large as a 49 CFR part 572, subpart N 6-year-old child dummy or a person, at the manufacturer's option, that is at least 21 kg in weight and 114 cm in height to define an occupied rear designated seating position for the purposes of testing the rear seat belt reminder system.”).

Back to Citation 20. See, e.g., id. at 410 (“NHTSA has concluded that it would . . . [be] appropriate to require that an occupant detection system be capable of detecting at least a 6-year-old.”).

Back to Citation 21.

                     Based on police-reported crashes documented in the Crash Report Sampling System (CRSS). Out of all sampled crashes from 2016-2022, 57 percent of rear seat occupants were 12 years old or younger.

Back to Citation 22. 88 FR 61674, See also Stephanie Huang and Matthew P. Reed (2006). Comparison of Child Body Dimensions with Rear Seat Geometry. Warrendale, PA: SAE International. The findings from this study were based on National Automotive Sampling System General Estimates System (NASS-GES) data. It also reported that approximately 70 percent of rear seat occupants of passenger cars, sport utility vehicles, and minivans are children under the age of 18.

Back to Citation 23.

                     Comment at pg. 6.

Back to Citation 24.

                     Comment at pg. 10.

Back to Citation 25.

                     Center for Disease Control Growth Charts for Children 2-20 years of age Data Files, published in May 2000 and available at *[https://www.cdc.gov/​growthcharts/​cdc-data-files.htm](https://www.cdc.gov/growthcharts/cdc-data-files.htm)* (last accessed April 23, 2025).

Back to Citation 26.

                     For more discussion, please see the FRIA (page 72).

Back to Citation 27.

                     For more discussion, please see the FRIA (page 87).

Back to Citation 28.

                     Wards Automotive Yearbook, based on average of MY 2017—MY 2021 data.

Back to Citation 29.

                     This additional allowance for the warning to deactivate if a rear door is opened is meant to address change-of-status events where the rear seat passenger opens the door to exit the vehicle after the change-of-status warning is activated, whereas, the door condition in the original regulatory text, that is unchanged by this final rule, prevents the warning from activating if any rear door is open when the change-of-status occurs.

Back to Citation 30.

                     S7.5(b)(1)(v) (“For a visual warning associated with multiple front outboard seats, the visual warning must clearly identify the seating positions for which the warnings are intended.”).

Back to Citation 31. 49 U.S.C. 30101 et seq.

Back to Citation 32. 5 U.S.C. 553(b)(B).

Back to Citation 33. United States v. Cotton, 760 F. Supp. 2d 116, 129 (D.D.C. 2011) (citing legislative history) (citations and quotations omitted).

Back to Citation 34. Mack Trucks, Inc. v. Envtl. Prot. Agency, 682 F.3d 87, 94 (D.C. Cir. 2012) (citations and quotations omitted).

Back to Citation 35. Id. at 95.

Back to Citation 36. Id.

Back to Citation 37.

                     Auto Innovators supplemental submission (Docket No. NHTSA-2024-0071-0008).

Back to Citation 38. Id.

Back to Citation 39.

                     NHTSA similarly believes that there is good cause to waive notice and comment with respect to the amendment to the regulatory text for the front seat belt first-phase audible warning. This amendment is a minor technical correction that clarifies the regulatory text so that it more clearly expresses the intent of the requirement, as explained in the preamble to the January 2025 final rule.

Back to Citation 40. 5 U.S.C. 553(d)(3) (exception to effective date requirement “as otherwise provided by the agency for good cause found and published with the rule”).

Back to Citation 41. 5 U.S.C. 553(d)(1) (exception to effective date requirement for “a substantive rule which grants or recognizes an exemption or relieves a restriction”).

Back to Citation 42. 49 U.S.C. 30111(d) (“The Secretary shall specify the effective date of a motor vehicle safety standard prescribed under this chapter in the order prescribing the standard. A standard may not become effective before the 180th day after the standard is prescribed or later than one year after it is prescribed. However, the Secretary may prescribe a different effective date after finding, for good cause shown, that a different effective date is in the public interest and publishing the reasons for the finding.”).

Back to Citation 43.

                     H.R. 3684 (117th Congress) (2021).

Back to Citation [FR Doc. 2026-06614 Filed 4-3-26; 8:45 am]

BILLING CODE 4910-59-P

Published Document: 2026-06614 (91 FR 17144)