Under a new rule, the EPA will require you to buy a minimum of four gallons of gas from any pump that sells E15, or gasoline that's 15% ethanol. Most stations sell E10, or 10% ethanol. But the handful of stations that sell E15, which made its debut two months ago, generally dispense it from the same pump as E10. Problem is, anyone who fills up with E10 after an E15 buyer could get as much as a quart of residual E15, American Motorcycle Association spokesman Peter Terhorst told the Milwaukee Journal Sentinel.
It's no big deal if you buy a lot of gas. But those who purchase just a few gallons — from motorcyclists to folks with lawn mowers — could damage their engines and void their warranties. Hence the four-gallon rule.
It's caused some controversy, most notably in an editorial Monday by Rep. Jim Sensenbrenner (R-Wis.): "E15 is like metal in a microwave for a small engine," he wrote. "Americans will try unsuccessfully to fill up a one- or two-gallon fuel can with E10 to take it home and use in their outboard boat engine or lawnmower. Even worse, what will happen when they take the fuel home, tainted with E15, and overheat their snow blower?"The EPA's rule should help mitigate this, to be sure, and most critics contend that the rule reflects bad gas — E15 — in the first place. The EPA certified vehicles back to the 2001 model year for the 15% ethanol blend, but automakers have demurred. The Auto Alliance, a trade association that represents 11 major automakers, raised concerns last May about potential engine failures. "Automakers did not build these vehicles to handle the more corrosive E15 fuel," Alliance President Mitch Bainwol said in a statement.
What's more, E15's lower energy density will lower gas mileage. As it stands, E10 already docks 3% to 4% in fuel efficiency compared with ethanol-free gas. Fill up with E15, and you can expect to lose a bit more.