The impact of the shrinking market could be felt for years to come, as automakers will continue to cut production and employment, and reduce the number of new vehicles they bring to the market.

“With these declines in revenues, you will see research and development budgets cut,” said Jesse Toprak, chief auto analyst for Edmunds.com, a Web site that offers car-buying advice. “We are going to have fewer new vehicles and less variety for at least the next couple of years.”

Mr. Toprak is forecasting sales of 12.4 million vehicles this year and 13.5 million in 2010. He said the chances of the industry reaching annual sales of 16 million were slim for the foreseeable future.

“The question is, What will be the natural level of demand in the U.S. market when the economy recovers?” he said. “Based on our best guess, it is probably in the range of 14.5 million to 15 million.”

Auto executives said on Monday that the industry had little chance of improving in the first half of 2009 because of a continued lack of available credit for prospective car buyers and a profound lack of confidence in an overall economic recovery.

“The first quarter is going to be bad no matter how you look at it,” said Emily Kolinski Morris, a senior Ford economist. “Once we get into the second quarter, we’ll have a better idea.”

G.M.’s chief market analyst, Michael C. DiGiovanni, said the automaker was predicting industry sales of 10.5 million to 12 million vehicles for the year.