Automakers including Chrysler Group LLC, Ford Motor Co. and Toyota Motor Corp. criticized an Environmental Protection Agency proposal to allow gasoline containing as much as 15 percent ethanol in all cars and trucks in the U.S., saying its use may void warranties.

Twelve automakers released letters today sent to Representative James Sensenbrenner, a Wisconsin Republican, saying the EPA proposal to sell so-called E15 fuel may damage engines and fuel-supply systems in vehicles made to run on gasoline with lower ethanol content. The EPA last week announced an orange and black label to be used at pumps selling blends containing 15 percent ethanol, reported Bloomberg.

“While Chrysler has been a strong advocate of renewable fuels, we have concerns about the potential harmful effects of E15 in engines and fuel systems that were not designed for use of that fuel,” Jody Trapasso, Chrysler’s senior vice president of external affairs, wrote in a June 23 letter to Sensenbrenner, vice chairman of the House Committee on Science, Space and Technology.

Sensenbrenner, in a letter today to EPA Administrator Lisa Jackson, said the decision to allow the fuel to be used in cars may sacrifice fuel efficiency as well as cause engine damage and void warranties.

“In difficult economic times, consumers need to get more miles from a gallon of gas and extend the lives of their cars,” Sensenbrenner wrote.

The EPA allowed the use of E15 fuel after working with the U.S. Energy Department to “ensure any increase would not have an adverse impact” on vehicles made since model year 2001, the agency said in an e-mailed statement.

“The administration will continue to take steps, guided by science and the law, to reduce our reliance on foreign oil and increase our use of home-grown fuels,” the agency said in the statement.

The other companies that sent letters were Bayerische Motoren Werke AG; Daimler AG’s Mercedes Benz; Honda Motor Co.; Hyundai Motor Co.; Kia Motors Corp.; Mazda Motor Corp.; Nissan Motor Co.; Volkswagen AG; and Volvo Car Corp., owned by China’s Zhejiang Geely Holding Group Co.