Committee on Technical Barriers to Trade - Notification - United States - Heavy-duty engines and vehicle fuel efficiency - Addendum



The following communication, dated 18 March 2024, is being circulated at the request of the delegation of the United States of America.





Title: Improvements for Heavy-Duty Engine and Vehicle Fuel Efficiency Test Procedures, and Other Technical Amendments


Reason for Addendum:

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Comment period changed - date:

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Notified measure adopted - date:


Notified measure published - date: 15 March 2024


Notified measure enters into force - date: 14 May 2024


Text of final measure available from[1]:

89 Federal Register (FR) 59481, Title 49 Code of Federal Regulations (CFR) Part 535:

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Notified measure withdrawn or revoked - date:

Relevant symbol if measure re-notified:

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Content or scope of notified measure changed and text available from1:

New deadline for comments (if applicable):

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Interpretive guidance issued and text available from1:

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Description: The National Highway Traffic Safety Administration (NHTSA) is finalizing minor technical amendments to the test procedures for heavy-duty engines and vehicles to improve accuracy and reduce testing burden. These amendments affect the certification procedures for fuel efficiency standards and related requirements. These amendments increase compliance flexibility, harmonize with other requirements, add clarity, correct errors, and streamline the regulations. Given the nature of these changes, NHTSA does not expect either significant environmental impacts or significant economic impacts for any sector.

This final rule is effective on 14 May 2024.

Title 49 Code of Federal Regulations (CFR) Part 535

This final rule and the proposed rule notified as G/TBT/N/USA/1917 is identified by Docket Number NHTSA-2020-0079. The Docket Folder is available on at and provides access to primary and supporting documents as well as comments received. Documents are also accessible from by searching the Docket Number.




[1] This information can be provided by including a website address, a pdf attachment, or other information on where the text of the final/modified measure and/or interpretive guidance can be obtained.