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Interpretation ID: honda-spw-jan172001



    William R. Willen, Esq.
    Managing Counsel, Product Regulatory Office
    American Honda Motor Co., Inc.
    1919 Torrance Boulevard
    Torrance, CA 90501-2746


    Dear Mr. Willen:

    This responds to your March 1, 2000, letter asking whether Honda's hybrid electric vehicles with "Idle Stop" automatic transmission systems are permitted under S3.1.3 of Standard No. 102, Transmission Shift Lever Sequence, Starter Interlock, and Transmission Braking Effect (49 CFR 571.102). Paragraph S3.1.3 states: "the engine starter shall be inoperative when the transmission shift lever is in a forward or reverse drive position." As explained below, we conclude that the systems on Honda's hybrid electric vehicles meet S3.1.3.

    You also asked about a 'gasoline engine version' of the Insight that Honda is developing. Detailed information, such as that provided to us regarding the automatic transmission hybrid electric vehicle Insight, is apparently not yet available for that version. Therefore, we will defer an opinion on that version until Honda can make available to the National Highway Traffic Safety Administration (NHTSA) similar information about it.

    As noted above, your letter described two future design vehicles that would use "Idle Stop" technology to conserve fuel and reduce exhaust emissions when the vehicle is normally stopped and idling. One is the Honda Insight hybrid-electric vehicle equipped with an automatic Continuously Variable Transmission (CVT). According to your letter, this vehicle uses both an electric motor and gasoline engine to provide motive power. The other vehicle is a "normal gasoline-engine vehicle" that would be equipped with an automatic transmission.

    Based on your letter and your discussions with NHTSA's engineers, we understand that the Honda Insight hybrid electric vehicle equipped with a CVT and Idle Stop Technology (IST) works as follows. The hybrid vehicle is designed so that the transmission shift lever must be placed in Park or Neutral when the driver manually uses the key to engage the starter to start the vehicle's gasoline engine. Honda believes this design feature enables the hybrid vehicle to comply with the original intent of S3.1.3.

    When the hybrid vehicle is driven with the transmission in Drive and the driver stops the vehicle with the brake, the IST shuts off the gasoline engine. When the driver subsequently removes his foot from the brake, the hydraulic brake fluid pressure is maintained, the transmission lever remains in Drive while the transmission itself electronically shifts internally from Drive to Neutral, the starter engages the gasoline engine, and the gasoline engine starts up. After the engine starts, the transmission shifts internally from Neutral back into Drive, the hydraulic brake fluid pressure is released, and the vehicle may start to creep forward. Honda engineers said that the vehicle will not lurch forward. To accelerate, the driver must depress the accelerator pedal. Honda believes that this automatic shut-off and restart sequence also meets S3.1.3, in that the driver's direct manual activation of the starter is not needed after the engine is initially engaged to start the vehicle.

    Toyota submitted a similar request for interpretation regarding its Prius hybrid vehicle. In an interpretation letter of October 22, 1999, to Toyota, NHTSA noted that the Prius has a drive train system that is more complex than those on vehicles that existed when Standard No. 102 was issued. The agency said that it will examine the requirements and conduct a rulemaking to update them as necessary. The agency concluded by saying: "Until that action is completed, we will interpret S3.1.3 of Standard No. 102 as requiring that driver activation of the engine starter must be inoperative when the transmission lever is in a forward or reverse drive position." (Emphasis added.) By "driver activation," we meant direct manual activation of the starter by the driver.

    Both the Prius and the Insight meet S3.1.3 as so interpreted.

    In stating this conclusion, NHTSA wishes to elaborate on its reasons for believing that there are safety concerns that must be addressed through rulemaking. The agency is aware that, besides Honda and Toyota, other vehicle manufacturers are currently designing vehicles with gasoline or diesel engine and hybrid propulsion plants that operate differently but attempt to achieve improved fuel economy. NHTSA does not wish to impede any of these efforts, but must be mindful of its safety responsibilities. The agency expects that those other vehicles, like the Prius and Insight, will have safety features that prevent sudden lurching forward or backward when the gasoline engine is restarted. Such lurching is a concern because it could result in a crash. Our rulemaking will address this and other potential issues.

    If you have any further questions, please feel free to contact Dorothy Nakama at this address or at (202) 366-2992.


    Sincerely,

    John Womack
    Acting Chief Counsel

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    d.1/17/01