27 February 2003
The German Umweltbundesamt (UBA, Environmental Protection Agency) completed a study, which found increased NOx emissions from Euro 2 diesel trucks on German roads. The UBA said that while the trucks met the Euro 2 standard during the regulatory test, they emitted up to more than two times more NOx when operated on the road.
The UBA concluded that the engines were programmed to meet the emission standards when tested on the 13-mode regulatory test cycle, but switched to more fuel efficient and higher NOx mode during highway driving.
The finding was disputed by the German automotive industry association (Verband der Automobilindustrie, VDA), who maintains that all trucks adhere to emission standards.
A similar discovery made in the USA by the EPA and the California ARB had led to the 1998 consent decrees between the EPA and a group of US engine manufacturers. The manufacturers used engine management software which switched to more fuel efficient driving modes during steady highway cruising, at the expense of increased NOx. This technique was considered an illegal “emission defeat device” by the EPA. Under the consent decrees, the manufacturers agreed to reprogram the affected engines, pay civil penalties, and spend additional funds on emissions research.