Why did American automakers produce no cars between 1942 and 1945 during World War 2?

American automakers didn't produce *passenger* cars between 1942 and 1945 because the factories were converted to war production. The resources, manpower, and manufacturing capacity of the auto industry were redirected to building military vehicles, weapons, and other war materials. This included things like tanks, jeeps, trucks, aircraft parts, and ammunition.