After meeting with lawmakers in May to encourage ethanol use, heads of General Motors Corp., Ford Motor Co. and DaimlerChrysler AG's Chrysler said in a letter to Congress they would double production of vehicles that run on ethanol and other renewable fuels by 2010, to at least 2 million annually, according to In a bid to cut reliance on imported oil and meet U.S. fuel-economy standards, GM now plans to "build and sell more than 800,000" flex- fuel vehicles for the U.S. by 2010, up from about 400,000 currently. Ford's output will double to about 500,000 and Chrysler's production will exceed 500,000, according to With more than 5 million flex-fuel autos currently in the U.S., GM projects that ethanol may account for 10 percent of automobile fuel within five years, compared with about 3 percent now. If all 2 million of the new GM, Ford and Chrysler models in 2010 run on E85, they would save more than 3.5 billion gallons of gasoline a year, the companies said.