U.S. regulators on Friday backed a request that would sharply boost the use of corn-based ethanol in more than half the nation’s cars, elevating the stakes in a contentious debate over the safety and cost of converting more corn into fuel.

The  Environmental Protection Agency’s announcement boosting the ethanol blend rate in gasoline to 15 percent from 10 percent in vehicles built from 2001 to 2006 was not a surprise, coming just months after it allowed the E15 in cars and trucks built in 2007 or later. Get the full story »