Automakers said Monday they are trying to get more ethanol-capable vehicles on the road quickly, but warned that consumers in the meantime should not use an E85 ethanol blend in conventional vehicles or try to convert their vehicles to use E85.

"Your vehicle was built a certain way for a certain reason. You really shouldn't tamper with that," Mary Beth Stanek, who manages General Motors Corp.'s (GM) partnerships with ethanol producers, told members of the U.S. House Agriculture Committee.

The committee was meeting at Oakland University in suburban Detroit.

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About 5 million vehicles on U.S. roads can run on E85, which is 85 percent ethanol and 15 percent gasoline. GM, Ford Motor Co. (F) and DaimlerChrysler AG (DCX) say they are capable of ramping up E85-capable vehicle production quickly as long as consumers are able to buy the fuel. About 685 of the nation's 165,000 fueling stations sell E85.

While E85 vehicles require special fuel injectors and other parts, all vehicles are capable of running on E10, which is a blend of 10 percent ethanol and 90 percent gasoline. Minnesota and Hawaii are the only states that require virtually all fuel sold to be E10, according to the American Coalition for Ethanol, an industry trade group. Montana, Washington and Missouri have passed similar laws but they're not yet in effect.

Gas stations may or may not be required to tell consumers they are using E10, depending on the state, but its use is widespread. Ethanol is now blended into about 35 percent of all of America's gas, coalition spokeswoman Kristin Brekke said.

U.S. Rep. Stephanie Herseth, D-S.D., said she fills up her conventional vehicle with a blend of about 30 percent ethanol and has been happy with its performance. South Dakota has the only two pumps in the nation that allow customers to choose a variety of blends, Brekke said.

But representatives from GM, Ford and other automakers warned that any blend with more than 10 percent ethanol can corrode parts on a conventional vehicle. Norbert Krause, director of the engineering and environmental office at Volkswagen of America Inc., said his company even makes technical adjustments depending on whether a vehicle will take a 10-percent or a 22-percent ethanol blend.

Herseth also asked about the cost of converting a conventional vehicle to one that can run on E85. Susan Cischke, Ford's vice president for environmental and safety engineering, responded that it's illegal for consumers to try to convert conventional vehicles because they won't be able to meet federal emissions standards once they're converted.

Krause said in the near term, the U.S. government should concentrate on making E10 available at every fuel station instead of expanding E85, since all vehicles can run on E10. The committee's chairman, U.S. Rep. Gil Gutknecht, R-Minn., introduced a bill late last year that would require virtually all fuel sold in the United States to be a 10-percent blend.

The oil industry doesn't support that legislation because it would make it more difficult and expensive to manufacture fuel, according to Bob Slaughter, president of the National Petrochemical and Refiners Association. The ethanol industry is already having trouble meeting a current mandate that will require production of 7.5 billion gallons of ethanol by 2012, he said.

"To require that every gallon in the U.S. contain ethanol is maybe, in ethanol country, a good aspirational goal but not a practical one," Slaughter said.

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