Automakers will make the largest fuel-economy increase to sport utility vehicles, pickup trucks and minivans in 20 years under new rules federal regulators issued April 1, according to the Detroit Free Press. The National Highway Traffic Safety Administration (NHTSA) will require automakers to raise the corporate average fuel economy for light trucks by 1.5 miles per gallon between model years 2005 and 2007. Environmentalists view the increase as too small, but automakers said that meeting the new fuel-economy standards will be a challenge, according to the Free Press. More than half the vehicles U.S. automakers sell are in the light-truck category. "In order to meet the target, we're going to have to change American buying habits," said Eron Shosteck, a spokesman for the Alliance of Automobile Manufacturers, which represents the automakers. "Nonetheless, we are committed to meeting it and working with NHTSA."