Volkswagen

Volkswagen: The scandal explained



It's been dubbed the "diesel dupe". In September, the Environmental Protection Agency (EPA) found that many VW cars being sold in America had a "defeat device" - or software - in diesel engines that could detect when they were being tested, changing the performance accordingly to improve results. The German car giant has since admitted cheating emissions tests in the US.

VW has had a major push to sell diesel cars in the US, backed by a huge marketing campaign trumpeting its cars' low emissions. The EPA's findings cover 482,000 cars in the US only, including the VW-manufactured Audi A3, and the VW models Jetta, Beetle, Golf and Passat. But VW has admitted that about 11 million cars worldwide, including eight million in Europe, are fitted with the so-called "defeat device".
The company has also been accused by the EPA of modifying software on the 3 litre diesel engines fitted to some Porsche and Audi as well as VW models. VW has denied the claims, which affect at least 10,000 vehicles.
In November, VW said it had found "irregularities" in tests to measure carbon dioxide emissions levels that could affect about 800,000 cars in Europe - including petrol vehicles. However, in December it said that following investigations, it had established that this only affected about 36,000 of the cars it produces each year.
This 'defeat device' sounds like a sophisticated piece of kit.
Full details of how it worked are sketchy, although the EPA has said that the engines had computer software that could sense test scenarios by monitoring speed, engine operation, air pressure and even the position of the steering wheel.
When the cars were operating under controlled laboratory conditions - which typically involve putting them on a stationary test rig - the device appears to have put the vehicle into a sort of safety mode in which the engine ran below normal power and performance. Once on the road, the engines switched out of this test mode.


Environmental campaigners have long argued that emissions rules are being flouted. "Diesel cars in Europe operate with worse technology on average than the US," said Jos Dings, from the pressure group Transport & Environment. "Our latest report demonstrated that almost 90% of diesel vehicles didn't meet emission limits when they drive on the road. We are talking millions of vehicles."
Car analysts at the financial research firm Bernstein agree that European standards are not as strict as those in the US. However, the analysts said in a report that there was, therefore, "less need to cheat". So, if other European carmakers' results are suspect, Bernstein says the "consequences are likely to be a change in the test cycle rather than legal action and fines".
It's all another blow for the diesel market.
Certainly is. Over the past decade and more, carmakers have poured a fortune into the production of diesel vehicles - with the support of many governments - believing that they are better for the environment. Latest scientific evidence suggests that's not the case, and there are even moves to limit diesel cars in some cities.
Diesel sales were already slowing, so the VW scandal came at a bad time. "The revelations are likely to lead to a sharp fall in demand for diesel engine cars," said Richard Gane, automotive expert at consultants Vendigital.
"In the US, the diesel car market currently represents around 1% of all new car sales and this is unlikely to increase in the short to medium term.
"However, in Europe the impact could be much more significant, leading to a large tranche of the market switching to petrol engine cars virtually overnight."