The U.S. Environmental Protection Agency may be close to settling a lawsuit brought against it by Cummins, International, and the Engine Manufacturers Assn. over tougher diesel emissions regulations.

Reuters reported this week that the EPA asked a federal judge to delay oral arguments in the lawsuit, saying "there is a reasonable prospect that the parties will be able to conclude settlement negotiations successfully."
The suit stems from the 1999 consent decree signed by most engine makers to settle a lawsuit filed by the federal government. The EPA claimed the engine makers were building engines with "defeat devices" - electronics that caused engines to meet the EPA's emissions tests, which mimicked in-city driving, but operated the engines differently, with more emissions, on the open highway. In the settlement, the engine makers agreed to meet EPA's 2004 emissions early - by October 2002.
At issue in the current lawsuit is the "not-to-exceed" provisions of the settlement, which set an absolute ceiling for diesel emissions regardless of operating conditions. The Engine Manufacturers Assn. says demonstrating compliance with the provisions is "impossible because you can't test engines under all possible conditions," an EMA spokesman told Reuters. "It's not a question of easing the standards," which environmental groups are concerned about. "It's a matter of how we need to comply with them."