For too long, no one suspected that any car manufacturer was cheating. Instead it was thought to be a weakness in the test
It is amazing that the Volkswagen and diesel emissions scandal was not discovered earlier. In 2003 nitrogen dioxide alongside London’s Marylebone Road increased by around 20%. As we approached the 2010 legal compliance date, concentrations from traffic went up, not down, and diesel cars were shown to be much more polluting than the official tests led us to believe.
However, according to the EU parliament’s recent inquiry, no one suspected that any car manufacture was cheating. Instead it was thought to be a weakness in the test.