Automakers are warning consumers not use an E85 ethanol blend in conventional vehicles that are not designed for the fuel or try to convert a vehicle to use E85.

Roughly 5 million specially designed flex-fuel cars and trucks on U.S. roads can run on E85, which is 85 percent ethanol and 15 percent gasoline. The others cannot.

E85 vehicles require special fuel injectors and other parts.

Any vehicle can burn E10, which is a blend of 10 percent ethanol and 90 percent gasoline.

Automakers warn that any blend of gasoline with more than 10 percent ethanol can corrode parts in a conventional vehicle. They also claim it would be illegal for consumers to try to convert conventional vehicles because the vehicles will not meet federal emissions standards once they're converted.

Automakers hope to ramp up E85 capable vehicle production quickly even though not all consumers are able to buy the fuel.

E85 is not easily available throughout the country. About 685 of the nation's 165,000 fueling stations sell E85 and most of them are in the Midwest.

Gas stations may or may not be required to tell consumers they are using E10, depending on state laws. Use of the fuel is widespread and growing. Ethanol is now blended into about 35 percent of all of the countrys gasoline.

The ethanol industry is already having trouble meeting a current mandate that will require production of 7.5 billion gallons of ethanol by 2012, according to one automaker.

"The bottleneck is distribution. The push to ethanol makes a great deal of sense regardless of the temporary price of gasoline," according to Ford CEO Bill Ford. "Even if it comes down dramatically, there still is the issue of where the oil is produced and the fact that we import virtually all of it."

The Big Three automakers have endorsed a bill that would offer a reimbursement of up to $30,000 to gas station owners who convert their pumps to renewable fuels. "If we want a game changer very quickly in big numbers, then ethanol is a very good play for this country," Ford said.