Top investors in the automotive industry painted a grim picture on Sunday for the sector in 2008, with one executive predicting a possible slump in U.S. sales to levels not seen in 15 years.

The weakest forecast is for a possible 9.4 percent decline. But all three investors - Jerry York, an adviser to billionaire investor Kirk Kerkorian; financier Wilbur Ross; and Thomas Stallkamp, a former Chrysler president - were more pessimistic than many in the battered industry.

"While I am very negative on the autos sector over the next 12 to 18 months, I'm just not sure how bad it could be," York, a former board member of General Motors Corp and chief financial officer of Chrysler, said at the Reuters Autos Summit in Detroit. "We all know housing is a debacle."

U.S. light auto sales could decline to 15.5 million or less next year, York said. That would be down from near 16 million this year, a drop of 3 percent to mark the second consecutive annual decline and the lowest tally since 1998.

Stallkamp, a partner at private equity firm Ripplewood Holdings, which owns several auto parts makers, said the market could slump to 14.5 million, the lowest level since 1993.

"I'd say it's somewhere between 14.5 and 15, somewhere in there and it's hard to tell," he said. "Today, I'm a little more towards 14.5."

Such a decline would be felt throughout the sector, CSM Worldwide auto analyst Michael Robinet said.

"That would certainly be one of the worst years on record given the gravity of the industry," he said.