BURLINGTON, Vt. --An auto industry consultant testified Friday that new rules to reduce carbon dioxide emissions from cars and trucks would devastate the auto industry if adopted, forcing the loss of at least 65,000 jobs over the next 10 years.

The testimony came during the ninth day of a U.S. District Court trial in which General Motors Corp., Daimler-Chrysler, two auto industry groups and three Vermont car dealers are suing to block rules adopted by Vermont aimed at reducing vehicle emissions of carbon dioxide, a greenhouse gas blamed by some for contributing to global climate change.

Ronald Harbour, who has advised car companies on industrial efficiency and other issues, said U.S. auto makers would lose sales if the carbon-reduction rules take effect as planned in California, Vermont and nine other states.

But under questioning from Sierra Club lawyer David Bookbinder, Harbour acknowledged that U.S. car companies already are shedding jobs by the thousands. Bookbinder introduced Securities and Exchange Commission filings in which General Motors said it was planning to close 12 plants and Ford Motor Co. 14.

Bookbinder questioned the assumption used by Harbour that, absent the regulation, auto industry employment in 2016 would remain where it was in 2006.

"We went with what we knew, because we wanted to hold it constant to see the effects of the regulation," Harbour said.

Harbour said there would also be more than 20,000 jobs lost in dealerships and distributors, and 41,000 indirect job losses in the economy at large if the rules take effect. He said his 65,000-job loss estimate conservative and said 200,000 jobs could be lost.

Vermont's rules mimic those drafted in 2005 by California and since adopted by nine other states.

The federal Clean Air Act allows California to adopt more stringent vehicle emission limits than those set by the federal government; other states may adopt California's rules if they choose.

The auto industry argues the only way to cut vehicle carbon emissions is to improve fuel efficiency and that, under federal law, only the U.S. Department of Transportation may set fuel economy standards. The auto industry also has sued to block the rules in California and Rhode Island, but the case in Vermont is the first to come to trial.

Bookbinder sought, through questioning, to make the point that the job losses would be tiny compared to the size of the car industry. The more than 20,000 jobs lost among distributors and dealerships would be out of more than 1.14 million, he said.

"If you're that GM dealer, that job loss is 100 percent to you and your family," Harbour replied.

Thomas Austin, a former official at the Environmental Protection Agency and California Air Resources Board, was called as an expert witness by the car companies.

But his testimony was barely under way when Simon Wynn, a member of the defense team, rose to challenge Austin's qualifications, using a series of questions focused on whether he had the knowledge and experience to talk about the technologies car companies might use to achieve the new standards.

He is expected to return to the stand Monday.