WASHINGTON -- Evolving vehicle technology and government regulation again are proving a prickly combination. Hybrids provide the latest example.
The emergence of hybrid cars and trucks forced federal regulators to rewrite a 35-year-old rule that requires a vehicle's starter to be inoperable when its transmission is engaged. Hybrids automatically turn gasoline engines off and on, so they can temporarily rely on fuel-saving electric power.
Last July, the National Highway Traffic Safety Administration finished the rewrite. It was scheduled to take effect at the end of last year.
But two years in the making, the revision didn't account for all hybrid variations.
So NHTSA did a quick U-turn in late December. It now says the rewrite will take effect in September 2007.
The delayed effective date is meant to give General Motors time to re-engineer part of its hybrid system, available on Chevrolet Silverado and GMC Sierra pickups.
GM found that its hybrid pickups would not comply with part of the rewrite. The new rule requires the brake pedal to be pressed before an engine restarts automatically with the transmission in reverse.
The automaker told NHTSA it is studying ways to modify its system to meet the requirement.
Last week, GM spokesman Brian Corbett told Automotive News that the change won't be a major undertaking. "We will do the necessary engineering and development" to comply, he said.
The requirement that starters be locked out when transmissions are in a forward gear or reverse was adopted in 1971. It sought to keep drivers from accidentally starting vehicles in gear, enabling them to lunge forward or backward.
But the rule did not anticipate hybrid vehicles.
Hybrids save fuel by automatically shutting off internal combustion engines under certain driving conditions, using electric propulsion only. The vehicles restart gasoline power when conditions change.
Until NHTSA could revise the rule, the agency tried a stopgap remedy. It advised makers of the first hybrid cars -- the Honda Insight and Toyota Prius -- that it would reinterpret the old rule to mean that drivers could not operate starters when transmissions are engaged.
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