European emission standards
This standard for nitrogen oxide emissions is among the most stringent in the world. For comparison, the contemporary [[European emission standards|European standards]] known as Euro 5 (2008 "EU5 compliant", 2009–2014 models) and Euro 6 (2015 models) only limit nitrogen oxide emissions to and respectively. Defeat devices are forbidden in the EU. The use of a defeat device is subject to a penalty.