http://money.cnn.com/2015/09/22/news/vw-recall-diesel/index.htmlhtml It turns out, Volkswagen's TDI "clean diesel" engines aren't that clean. Their engines have been discovered to have programming designed to fool emissions tests. In reality, they produced 40 times more nitrogen oxide than is permitted by the US EPA. The programming is in 11 million vehicles in the US and Europe, and may also affect diesel engines put in Audi cars.