Diesel dilemma - the Volkswagen emissions scandal

The big news in the automotive world last week was the discovery that Volkswagen (VW) vehicles have been using software specially designed to cheat in order to pass strict US emissions tests for its diesel engine cars. A small non-profit organisation called the International Council of Clean Transportation (ICCT) performed tests on the VW Passat and VW Jetta, initially to show that diesel-fuelled vehicles could run with cleaner emissions as demanded by the US's very strict regulations. What they discovered was quite the opposite, however, revealing that the vehicles were in fact breaching the US regulations by up to 40 times the emissions standard allowed. A wide-ranging plot to cheat the emissions testing was soon revealed in which the cars' software would reduce performance when under test conditions, thus reducing the harmful emissions produced. But what exactly are the environmental consequences of the emissions in question and what does this mean for VW drivers