Volkswagen UK boss Paul Willis has admitted that his company's so-called 'defeat device' did affect the results of emissions tests in Europe.

Previously, the German manufacturer has only confirmed that the software-based emissions cheat was present on some vehicles in Europe - and has not outlined whether the defeat device was active during the NEDC emissions test used across the EU.

However, when asked during a 45-minute grilling from MPs on the transport select committee if the defeat device had been used during type approval testing for the UK, Willis admitted, "It seems from what I understand - and I'm not an engineer - that the system of gas regulation in the engine influenced the NOx output in cars that we sell in the UK. These cars are type approved across all of Europe, of course, and they're type approved in Germany, with separate people overlooking it.
"We mishandled the situation in so far as our engines behaved differently within the testing regime to the real world. That's why we need to fix the cars, that's why we need to get the customers in, and that's why we need to put the cars right. We mishandled the situation, without a shadow of a doubt.

"It seems that in the test regime the engine behaved differently to the real-world situation via software. The software affected the flow of gas to the engine which reduced the NOx."

UK's 1.6 diesel fix won't need a new urea tank

Of the 1.2 million affected cars in the UK, Willis said 400,000 - believed to be those with the 1.6-litre version of the EA189 diesel engine - would need additional corrective work beyond a software upgrade, including new fuel injectors, and that this would "take a longer period of time".
However, he said that the installation of exhaust after-treatments, likely to be fitted to some cars affected in the US in the form of a urea tank, would not be necessary in the UK. "My understanding is that the addition of urea tanks is not part of the solution in Europe," he stated. "There's a different technical configuration on the cars and different technical regulations apply. My understanding is that the costs are different, too."

The remaining 700,000-odd units - 2.0-litre diesels and around 30,000 1.2-litre diesels - can be fixed by software patches alone.

While details on the technical fix Volkswagen will use to correct the affected cars remain limited, Willis said that customers should notice no difference in fuel economy once the fix has been applied. "Our engineers are working to the brief that there cannot be any change in miles per gallon," he said.