NHTSA Questions IDLE STOP

The very idea of turning your car s engine off every time you come to stop and then restarting it when you are ready to move again sounds pretty hideous. Yet for the last few years several automakers have been working on technology that does just that. When you brake and come to a stop, the engine shuts down. When you press the accelerator, the engine restarts. General Motors actually tested prototypes of the concept in the 1970s during the last energy crisis. Proponents of the technology say it saves fuel and reduces emissions. In a state like California where cars spend more time at rest in traffic than moving, the cutback in emissions could be significant.

The technology, however, has its doubters and yesterday a big one reared its head. NHTSA told Honda Motor Co. yesterday that it wanted more time to study vehicles equipped with what Honda calls Idle Stop. There is a concern, an agency spokesperson said, over sudden lurching forward or backward in vehicles with similar technology. NHTSA has not evaluated the Honda technology as yet.

The concept of Idle Stop vehicles stems from electric vehicles, which do shut down while at a stop, sort of the way you turn a light switch on and off. Generally, however, torque values are much lower in electric cars and the transmissions are different. Adapting a conventional automatic transmission to shut down the engine and then restart it and pull away smoothly is a tall order. Honda believes it has solved the lurching problem.

In the meantime, NHTSA told Honda it will defer an opinion on Idle Stop used in gasoline engines until it learns more about it. The agency has asked Honda for more technical information.