The VW Emissions Scandal is all to do with attempts to make Diesel cars more environmentally friendly. Originally, in 2005, Volkswagen was due to purchase the Mercedes BlueTec system for reducing diesel pollution but they decided to come up with their own system in the end. However, VW struggled to make their VW diesels clean whilst still providing good fuel economy.
The US market has always been more wary of diesel vehicles where they get more of a bad press than in Europe. Also, in the US, the diesel emissions requirements are significantly stricter than in Europe. For this reason VW decided the only way they could get their vehicles to pass US emissions tests, whilst also providing good fuel economy, was to change the behaviour of their diesel vehicles when they were being tested to appear cleaner than they were on the road.
VW made the conscious decision to program the engine control to switch from better fuel economy and higher emissions output to a lower-emission, compliant mode when being tested. The EA 189 is the main diesel engine cited for this behaviour. This meant the affected diesel engines polluted terribly under normal circumstances, but passed strict tests in the lab.
Contrary to some reports, Der Spiegel reported that at least thirty management level employees at Volkswagen were aware of the deception for a number of years. VW deny this.
VW made good use of their fraudulently obtained emissions results, using these credentials to obtain 'green car' subsidies in the US and making a marketing point of their environmental credentials. Some notable awards VW were happy to receive for their emissions performance included: