The Environmental Protection Agency (EPA) denied three petitions by industry groups that requested a re-examination of Clinton-era rules requiring cleaner diesel trucks and buses, the Associated Press reported. The Bush administration has said it would stand by the rules, but the American Trucking Associa-tions, the American Petroleum Institute and Mack Trucks/Volvo Powertrain each petitioned the EPA to take another look. The agency said the decision not to re-examine the rules was based on a review of the petitioners’ arguments, according to AP. Christie Whitman, the EPA chief, has been previously quoted as saying that cleaner diesel vehicles can help states meet federal clean air standards, AP said. Beginning with the 2007-model year, diesel vehicles will be required to use engines that produce lower amounts of particle soot. Vehicles will also have to produce less nitrogen oxide by 2010 under the new rules, AP said. The story also said the rules could increase the price of a diesel engine by $1,200 to $1,900, and boost the price of diesel fuel by at least 4 cents per gallon.