DETROIT (Reuters) - Three Congressional leaders on Monday asked top federal environmental and safety officials to extend by 60 days the public comment period on new vehicle emissions and fuel economy standards. The public and their advocates need more time, beyond the comment period that ends Sept. 26, to absorb more than 1,000 pages of a draft technical assessment report, the three said in a letter to the environmental and safety chiefs. A week ago, U.S. regulators denied a similar request for an extension by major automakers. The U.S. Environmental Protection Agency and the National Highway Traffic Safety Administration said in a July report that automakers have the technology to meet aggressive mandates to hike fuel efficiency, but improvements will not be as great as the Obama administration once forecast because buyers are switching to pickup trucks and sport utility vehicles from lighter cars.         When the administration first outlined its goal of boosting average fleet fuel economy to 54.5 miles per gallon, regulators forecast that 67 percent of vehicles sold in 2025 would be cars.     Since then, gasoline prices have fallen and truck and SUV sales have surged.      Regulators now estimate the fleet will average 50 to 52.6mpg in 2025. The letter dated Monday was sent to EPA Administrator Gina McCarthy and National Highway Traffic Safety Administration Administrator Mark Rosekind. It was signed by three members of the U.S. House of Representatives: Fred Upton, chairman of the Committee on Energy and Commerce; Ed Whitfield, chairman of the Subcommittee on Energy and Power; and Michael Burgess, chairman of the Subcommittee on Commerce, Manufacturing and Trade. 
Congressional leaders ask for more time to study new fuel rules