Federal regulators will propose benchmarks Tuesday for automakers to hit on their way to reaching a fuel-economy requirement of 35 miles per gallon by 2020. Auto fleets will have to average 27.8 mpg by 2011 and 31.6 mpg by 2015 — a more aggressive timetable than was required by Congress. That’s 35.7 mpg for passenger cars in 2015 (new cars averaged 31.3 mpg last year) and 28.6 mpg for light trucks (new trucks averaged 23.1 mpg last year). The proposal manages to gain acceptance from both automakers and enviros. Alliance for Automobile Manufacturers spokesfolks said the numbers will “stretch the industry to innovate” and that “automakers are prepared to meet that challenge”; the Sierra Club’s Dan Becker says, “I think you need to give the Bush administration credit. They got one right.” The proposed standards are timed nicely to Earth Day, and come one day after the average price of gasoline in the U.S. topped $3.50 a gallon for the first time.