Automotive output is headed for a longer and more painful downturn in the U.S. than had been expected. Economists say sharp declines every month since June have hit Detroit's Big Three and the Japanese-owned automakers. Morgan Stanley now forecasts light vehicle sales of 16.4 million this year, down from an earlier estimate of 16.7 million. That's why General Motors Ford and newly independent Chrysler have cut autumn production of full-sized pickup trucks and sport-utility vehicles.