Auto makers see future in hybrid, diesel engines.

DETROIT - Sustained consumer interest in cars that use alternative energy sources, such as hybrid and diesel engines, will largely depend on U.S. gasoline prices remaining high, auto industry executives said at the Reuters Autos Summit in Detroit this week. "If gasoline falls significantly below $3 a gallon and stays down below $3 a gallon, you undercut the economic viability of all these alternatives," said Mike Jackson, chief executive officer of AutoNation Inc., the United States' largest car retailer.