EDIT
Senators Carl Levin and Debbie Stabenow, both of Michigan, are drafting a bill that would raise mileage requirements but would be more lenient for light trucks and would give car companies the possibility of an escape hatch by demonstrating that the rules would be too costly to meet. The Senate Democratic leader, Harry Reid of Nevada, hinted at the lunch on Wednesday that he was willing to look for a compromise. Noting that the industry and the United Automobile Workers union were at least willing to support some increase in mileage requirements, Mr. Reid said he was ready to listen. “I haven’t seen all the details yet,” he told reporters, “but I hope that we can work together to make substantial progress.”
Environmental and consumer groups warned Wednesday that Democrats were in danger of diluting the requirements until they had little meaning. “The question is no longer whether Congress will act on fuel economy, but whether what it passes will mean anything,” said Kevin Curtis, vice president of the National Environmental Trust, an advocacy group in Washington.
The House speaker, Representative Nancy Pelosi of California, is on a collision course with Representative John D. Dingell of Michigan, chairman of the Energy and Commerce Committee. Mr. Dingell and Representative Rick Boucher, Democrat of Virginia, have drafted a bill that calls for raising the fuel efficiency requirement for passenger cars to an average of 36 miles a gallon and for light trucks to 30 miles a gallon by 2022.
But the bill includes escape hatches from the rules if car companies can demonstrate that the requirements would be too difficult to meet. (Ed. - emphasis added)
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http://www.nytimes.com/2007/06/07/business/07energy.html