WASHINGTON - The Environmental Protection Agency's impending decision this summer on whether to grant an E15 waiver request -- a move that would increase the amount of ethanol that could be blended in gasoline from 10 to 15 percent -- continues to stir plenty of debate. The issue essentially pits the ethanol industry against the auto and oil industries. 

The Alliance of Automobile Manufacturers, citing new test data, argues that E15 has the potential to damage cars and increase the amount of pollution they emit, the New York Times reported. According to the group, half of the engines tested thus far have shown problems. Higher blends of ethanol can confuse exhaust control systems and cause engines to run too hot, and E15 can damage catalytic converters and engine cylinders, the group argues. Automakers are urging the EPA to delay any policy changes on ethanol blends until after 2011 to allow for further testing. 

But the ethanol industry continues to push for the waiver, arguing it is needed to reduce reliance on imported oil. The Renewable Fuels Association this month also asked the Obama administration to immediately allow for the blending of E12, in response to the Gulf of Mexico oil spill. The RFA noted that it believes that oxygenate stacking rules permitted by the Clean Air Act already provide the flexibility to blend up to 12 percent oxygenate, including ethanol.