AMIA members General Motors, Ford Motor, Chrysler, Nissan Motor and Volkswagen have been idling plants, reducing shifts and laying off staff because of the decline, according to the statement.
Auto export sales have fallen 42.1 percent, compared to the same period of last year, AMIA said.
Domestic sales is also suffering a 30.7 percent slump, hit by contagion from the United States and by a credit crunch which has bashed demand among consumers, the association reported.