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Mr. Michael D. Payne

One Thorton Court

Potomac Falls, VA 20165

Dear Mr. Payne:

This responds to your letter concerning the speedometer marking requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 101, Controls, telltales and indicators. You ask whether vehicles can have km/h primary and mph secondary.

By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal Motor Vehicle Safety Standards (FMVSSs) for new motor vehicles and new items of motor vehicle equipment. See 49 U.S.C. Chapter 301. FMVSS No. 101 is one of the standards we have issued.

FMVSS No. 101 requires speedometers to be labeled with MPH, or MPH and km/h. See Table 1. The intent of the standard is to require speedometer display in miles per hour (MPH), and to allow the addition of kilometers per hour (km/h) to MPH at the option of the manufacturer. The standard does not permit speedometers to be graduated in km/h only, since speed limits in the United State s are communicated on highway signs in MPH alone.


The standard specifies that if the speedometer is graduated in both miles per hour and in kilometers per hour, the scales must be identified MPH and km/h, respectively. The standard does not specify, in this situation, that MPH must be primary. However we would not provide a specific interpretation in this area outside the context of a specific design.


You state that this provision of FMVSS No. 101 appears to be in violation of Federal law since it was the intent of Congress to designate the metric system as the preferred system for the United States. Moreover, your letter states that you petition NHTSA to change the wording to comply with Federal law. We believe that FMVSS No. 101 is a legally valid exercise of NHTSAs regulatory authority and is not contrary to any Federal law.

We note that NHTSA ordinarily uses the metric system in its FMVSSs. However, the agency is not required to specify the FMVSSs in metric units only. In this particular instance, for reasons explained above, there is a safety reason why the agency does not permit speedometers graduated in km/h only.

Your letter does not meet minimum requirements for NHTSA to consider it a petition under 49 CFR Part 552 Petitions for Rulemaking, Defect, and Noncompliance Orders. Thus, your letter has not been treated as a petition.

I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.

Sincerely yours,

Anthony M. Cooke

Chief Counsel