Well, now motorists frustrated over a possible expansion of E-15 can thank automakers for getting involved in the battle over an increase in ethanol content.

From autoweek:

Automakers are seeking to head off an EPA ruling that would allow gasoline to contain 15 percent ethanol, up from 10 percent now, and they've won some bipartisan congressional support.

The two main automaker industry lobbies have argued that the U.S. Department of Energy has done insufficient testing to assure that gasoline containing up to 15 percent ethanol won't harm vehicles.

Increased ethanol composition could affect engine durability, emissions, driveability and on-board diagnostics systems, the Association of International Automobile Manufacturers says.

In a Sept. 21 letter to the EPA, the other automaker lobby, the Alliance of Automobile Manufacturers, wrote: "It is in the best interest of all participants, including EPA, DOE and the ethanol industry, that the agency not rule prematurely on such a sizable change significantly impacting government, industry and a huge national market of consumers."

Tests being performed by the industry and academia probably will be completed within a year, said General Motors Co. spokeswoman Sharon Basel.

The EPA, responding to a request from ethanol makers, expects to make a final decision this fall on whether to raise the allowable ethanol portion of gasoline to 15 percent from the 10 percent limit set in 1979, spokeswoman Cathy Milbourn said.

The Energy Department soon will complete testing to determine the impact of higher ethanol blends on vehicles built after 2007, she said. The agency also is testing some vehicles built before 2007, as well as tanks and other fuel-handling equipment, to see how they might be affected by the higher ethanol blend, known as E15, Milbourn said.

Ethanol- a brief history:

1979: EPA allows gasoline with as much as 10% ethanol.

Dec. 2007: Energy Independence and Security Act sets annual ethanol production target of 15 billion gallons by 2015.

March 2009: Ethanol producers ask EPA to raise ethanol limit in gasoline to 15% so they can meet 2007 law.

Fall 2010: EPA decision is due on request from ethanol producers.