Daimler Trucks North America LLC, Detroit Diesel Corp., Mack Trucks Inc., and Volvo North America LLC sued the Environmental Protection Agency October 26 in the U.S. Court of Appeals for the District of Columbia Circuit after it issued a rule allowing Navistar Inc. to pay nonconformance penalties for truck engines that fail to meet federal NOx standards. The agency issued a final rule September 5 allowing Navistar Inc. to produce heavy-duty diesel engines as it transitions to new emissions control technology in 2012 so long as it pays a $3,775 per engine penalty.