It's a dilemma for drivers: Do they choose a gasoline that's cheaper and cleaner even if, as opponents say, it could damage older cars and motorcycles?
That's the peril and promise of a high-ethanol blend of gasoline known as E15. The fuel contains 15 percent ethanol, well above the current 10 percent norm sold at most U.S. gas stations.
The higher ethanol blend is currently sold in just fewer than two dozen stations in the Midwest, but could spread to other regions as the Obama administration considers whether to require more ethanol in gasoline.
As a result, there's a feverish lobbying campaign by both oil and ethanol interests that has spread from Congress to the White House and the Supreme Court.