Flex-Fuel Amendment Makes for Strange Bedfellows Faced with a bill that would require 80 percent of gasoline-burning cars and trucks to be compatible with ethanol and methanol by the 2018 model year, stakeholders who typically disagree on critical issues find themselves in a rare position. They agree. The legislation, known as the Open Fuels Standard Act of 2011 and introduced in the Senate last September by the Washington Democrat Maria Cantwell and Indiana Republican Richard G. Lugar, was proposed as an amendment to the pending Senate version of the contentious transportation bill. Environmentalists and automakers, as well as the United States Chamber of Commerce, the Competitive Enterprise Institute and the American Meat Institute, are united in their opposition to the legislation. In a letter addressed Monday to House and Senate majority leaders, the groups said that consumers who wanted flex-fuel vehicles could already buy them. "Currently, there are nearly 10 million flex-fuel vehicles (F.F.V."s) on U.S. roads, yet on average they use less than a single tankful of E85 per year," it said, referencing the ethanol formulation also opposed by environmental groups and automakers. The letter's authors went on to describe the proposed amendment as "a misguided consumer mandate that will lead to unintended consequences on vehicle manufacturers, the supply chain and emerging technologies." Under the bill, so-called flex-fuel cars and trucks, which can run on ethanol or gasoline, would be labeled Fuel Choice-Enabling Vehicles. "Phasing in vehicles that can run on fuels other than petroleum will allow a whole host of new domestic sources of transportation fuel to come online, which should reduce our dangerous overdependence on foreign oil and help keep American dollars here at home," Ms. Cantwell said in a statement. The amendment attracted praise from the United States Energy Security Council in Washington, which said in a letter Thursday that the proposal was "the simplest, least-cost approach for reducing the strategic importance of oil and the corresponding liability of gasoline price spikes that wreak havoc on our economy and American family budgets." The council includes Tom Ridge, the former governor of Pennsylvania and former secretary of homeland security, and Mary E. Peters, the former secretary of transportation, who co-authored an editorial that appeared in The Times on Feb. 23 in favor of prioritizing the production of methanol. The former central intelligence director, James Woolsey, and a former national security adviser, Robert McFarlane, co-signed the letter sent Thursday. Environmentalists, including those who support research into advanced cellulosic ethanol from plants, reacted coolly to the proposal, which was criticized for supporting the current corn-ethanol infrastructure. "This bill is too aggressive," David Friedman, deputy director at the Clean Vehicles Program of the Union of Concerned Scientists, said in a telephone interview. There may be a time when we need to require auto companies to add alternative-fuel technology to their vehicles, but this legislation moves too far, too fast. In an e-mail, Gloria Bergquist, a spokeswoman for the Alliance of Automobile Manufacturers, which represents the interests of the 12 biggest automakers in the United States, called the proposal a ""Field of Dreams" mandate." Her assessment had support from Dan Becker, director of the Safe Climate Campaign at the Center for Auto Safety, an organization that has often opposed the alliance on critical issues. "Once a century, the auto industry is right," he wrote in a an e-mail.