Volkswagen ordered to recall 500,000 cars due to emissions cheating

Previously: https://news.ycombinator.com/item?id=10240001

NOx emissions are tricky. They're created by high temperatures (the reaction is endothermic).

Conversely, the hotter the engine runs the more efficient it is. To a first approximation NOx is inversely related to CO2 emissions and l/km.