Search Interpretations


Mr. Jacques Bolduc

SRD Bolduc, Inc.

12521 St.-Charlotte Drive

Tampa, FL 33618

Dear Mr. Bolduc:

This responds to your letter concerning Federal Motor Vehicle Safety Standard (FMVSS) No. 124, Accelerator Control Systems. That standard specifies requirements for the return of a vehicles throttle to the idle position when the driver removes the actuating force from the accelerator control, or in the event of a severance or disconnection in the accelerator control system. You wish to know of foreseeable concerns that a vehicle equipped with an engine and a parallel hybrid electric vehicle drive may have with complying with FMVSS No. 124. We address your question below.

By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue and enforce the FMVSSs for new motor vehicles and new items of motor vehicle equipment. NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Instead, manufacturers are required to certify that their vehicles and equipment meet applicable standards. NHTSA enforces compliance with the standards by, among other things, purchasing and testing vehicles and equipment, and we also investigate safety-related defects.

Your letter stated that your client, a final stage manufacturer, completes an incomplete heavy duty vehicle by adding various bodies and a parallel hybrid electric vehicle drive system. You expressed concern about whether the completed vehicle can meet FMVSS No. 124 because:

The hybrid system provides, in addition to providing electrical power to truck mounted equipment, power assist (acceleration) on a decreasing level. The power assist operates at RPMs below 3600 and speeds below 40 MPH. The higher the RPM and the vehicle speed, the less input from the power assist.

In a telephone conversation with Dorothy Nakama of my staff, you stated that the incomplete vehicle manufacturer provides a gasoline or diesel engine to the vehicle. Your client places an electric power assist system that is intended to function when the vehicle speed is less than 40 miles per hour (MPH). The electric power assist system works in parallel with the gasoline or diesel engine and is intended to provide additional torque at lower speeds. Cutting back on torque required for the gasoline or diesel engine results in reduced fuel consumption. You stated that whether the vehicle is propelled by the engine or the electric power assist system is determined by the vehicle. The driver does not control whether the vehicle is propelled by the engine or the electric power assist system.

As noted above, you asked whether there are any foreseeable concerns with the compliance of a vehicle equipped with such a power assist in regards to the requirements of FMVSS 124. While we can provide information about our standards and respond to specific requests for interpretation, we are unable to provide technical analysis of specific products. As noted above, manufacturers have the responsibility to ensure that their vehicles meet applicable Federal motor vehicle safety standards, and to make required certifications. As a final stage manufacturer, your client should, among other things, be familiar with 49 CFR Parts 567, Certification, and 568, Vehicles Manufactured in Two or More StagesAll Incomplete, Intermediate and Final-Stage Manufacturers of Vehicles Manufactured in Two or More Stages.

We note that the requirements of FMVSS No. 124 apply to the performance of the vehicle, rather than to individual propulsion systems. Therefore, for vehicles with multiple or parallel propulsion systems, the vehicle must meet the requirements of the standard regardless of what propulsion system(s) may be operative. Thus, when the accelerator control is released or a single point disconnection occurs in the accelerator control system, the throttle must return to the idle position within the time specified by the standard so as to prevent engine overspeed and unintended propulsion from any and all sources.

I hope this information is helpful. If you have any questions, please contact Ms. Nakama at (202) 366-2992.

Sincerely yours,

O. Kevin Vincent

Chief Counsel

Dated: 9/22/09