The dismal sales reports for December punctuated the worst year for vehicles sales since 1992. Sales dropped 31 percent at G.M., 32 percent at the Ford Motor Company and a stunning 53 percent at Chrysler, a unit of the private equity firm Cerberus Capital Management.

Foreign automakers hardly fared better, with sales plunging 37 percent at Toyota, 36 percent at BMW and 35 percent at Honda.

While the Bush administration approved up to $17.4 billion in loans to G.M. and Chrysler, analysts say they expect the Detroit auto companies to need longer-term assistance from the incoming president, Barack Obama.

“The internal problems of the Big Three are so great, there is no way they can survive without government help for several years,” Mr. Casesa said.