Mr. Douglas said the industry supported improving mileage standards, but warned that forcing automakers to increase mileage would cost jobs, make cars less safe and harm the economy.

Nationwide car sales were predicted to fall as much as 25%, forcing automakers to reduce production in October-2010 from the prior level of 200 cars per day.

After Congress passed legislation forcing automakers to act in 1975, average mileage almost doubled to 27.5 miles a gallon in 1987 from 14 in 1972.

Previously, falling sales of S.U.V.s and trucks forced American automakers to lay off tens of thousands of workers, further punishing the economy.

While regulations have indeed forced automakers to act against emissions of smog-forming pollutants, the advertisements essentially ignore greenhouse gases like carbon dioxide as an automotive emission.

The regulatory system adopted 30 years ago, they say, led to unnecessary deaths by forcing automakers to produce cars that were too small, light and unsafe.

A backlog of unsold vehicles has forced automakers to cut production, which means that suppliers like Collins & Aikman must also pull back - and capital spending is not spared.

In 2002, she voted against "a proposal that would have forced automakers to create vehicles with fleetwide averages of 40 miles-per-gallon by 2015 - 'a strong, national fuel economy standard'."

California regulators, as well as environmental groups, counter that the rule has forced automakers to accelerate the development of cleaner technologies with sound prospects.

Ultimately, many analysts say that rising gas prices could supersede regulation as the prod to finally force automakers to produce vehicles that are more fuel-efficient than Lincoln Navigators.