Toyota, Honda, and BMW report declines of 30 percent or more in December.
GMAC's president says the federal money will have an immediate impact on the credit it can offer General Motors customers.
Even if it adds up to $8 trillion, the final cost will be lower as US sells the assets it's now buying.
Until then, employment, output, and housing prices will keep falling.
How firmly will he stand with his labor allies during the painful restructuring of the auto industry?
Plans for lengthy plant shutdowns hint at a turning point in automaker history.
Readers write about retooling the UN Human Rights Council; why auto suppliers need a bailout, too; the Federal Reserve's role in creating the housing bubble; and barring illegal workers from US jobs.
Congress's rescue of financial institutions may prove the exception, as automakers learned last week.
US could tap $700 billion financial-rescue fund to keep automakers afloat temporarily.