Interpretation ID: nht81-2.33

DATE: 06/17/81

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Volkswagon of America, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of May 27, 1981, asking for an interpretation of Motor Vehicle Safety Standard No. 108. Your company is considering, for fuel economy purposes, use of an engine stop/start system by which the engine would be switched off within a few seconds after a vehicle has come to a complete stop, and, to save battery capacity, the headlamps would also be deactivated. The parking lamps, however, will remain on. You believe that Standard No. 108 would not preclude such a system.

Although your letter does not mention it, we assume that when the parking lights are activated, the taillamps, license plate lamps, and side marker lamps would also be on, as required by S4.5.7(a) of Standard No. 108. The question then arises whether the system described is prohibited by paragraph S4.1.3 which states that "No . . . motor vehicle equipment shall be installed that impairs the effectiveness of lighting equipment required" by Standard No. 108. Although the primary function of headlamps is to illuminate the roadway in front of the driver at night or under conditions of reduced visibility, they also serve to indicate the presence of the vehicle to traffic approaching from the opposite direction. In a situation where, on a two-lane road, a car has pulled to the shoulder temporarily, a headlamp will be perceived at a greater distance than a parking lamp to oncoming traffic. Headlamps also serve an illuminating function when people have paused in unfamiliar neighborhoods in an effort to discern their whereabouts. We believe, therefore, that your device could be viewed as impairing the effectiveness of headlamps within the meaning of S4.1.3.

This, however, is not a view dispositive of the issue. Compliance with Standard No. 102 would also appear to be affected as that standard requires that the engine starter be inoperable when the transmission shift lever is in the forward or reverse position. Last year the agency granted a rulemaking petition with respect to an engine stop/start system such as you have discussed. I enclose a copy for your information. Although no notice has yet been published on this question, we shall endeavor to include a reference to headlamp switching devices in any future rulemaking activity on this subject.

ENC.

MAY 27, 1981

Frank Berndt Chief Counsel National Highway Traffic Safety Administration

SUBJECT: Request for Interpretation - FMVSS 108

In order to further improve fuel economy, Volkswagen is investigating the possibility of using an engine stop/start system. This system would automatically switch the engine off within a few seconds after the vehicle has come to a complete stop. When the accelerator is depressed the engine will start again automatically (or, on vehicles with manual transmission, it will start when the gear shift lever is put into first gear). We estimate a fuel savings of 6 to 10 percent, a significant reduction in exhaust emissions and noise pollution with the stop/start system in city driving conditions.

In order not to excessively burden the battery capacity, the stop/start system will have to use a switch mechanism which turns the headlamps off together with the engine. The parking lights will remain on. Once the engine is restarted, the headlamps will be switched on automatically.

When reviewing FMVSS 103, Volkswagen concluded that the standard would not preclude an automatic headlamp switching system as described above. We request your interpretation as to whether Volkswagen's conclusion concerning automatic headlamp switching systems is correct. Your early response to this will be greatly appreciated.

Dietmar K. Haenchen Executive Engineer Vehicle Regulations