Diesel cars are emitting up to 14 times more pollution than previously thought amid warnings that manufacturers have been misleading the public.
The first government analysis of cars conducted following the Volkswagen emissions scandal found that all vehicles substantially breached limits on levels of deadly nitrogen oxide.
The £1 million investigation found no evidence that “defeat device” software, which was fitted to VWs to cheat emissions tests, had been found in other models. However, manufacturers employed another system that reduced pollution in a test environment but shut down in cold weather, causing emissions to rocket when cars were driven on the road.
Ministers said the system was legal but admitted they were shocked by the scale of non-compliance associated with the technology.
The conclusions may open the door to multimillion-pound legal claims against motor manufacturers in the UK amid warnings that owners were cheated into buying cars that had much higher pollution levels than advertised. It could also lead to heavy fines being levied on companies when new EUwide tests are introduced next year to bring emissions levels closer to realworld driving conditions.
Last night, the disclosure led to accusations from Labour that the government had failed to get a grip on pollution despite being told two years ago that diesel emissions were being routinely breached.
Lilian Greenwood, the shadow transport secretary, said: “There can be little confidence in the government’s ability to tackle the problem.”
The government tested 37 diesel cars to see how they performed after being driven for 90 minutes on public roads. Cars registered from January 2011 were tested against the Euro 5 standard of 180mg/km, which applied to vehicles sold up to September. All the results were “substantially higher”, reaching an average six times the limit. The Vauxhall Insignia had 1,881mg/km, more than ten times as high. The Range Rover Sport had 1,720mg. Another test benchmarked newer cars against the more rigorous Euro 6 standard of 80mg/km, which was introduced from September. Cars were an average six times over the limit. The worst offender was the Peugeot 3008, at almost 14 times the legal level. Other serious breaches were registered by the Mercedes A180, Renault Megane and Vauxhall Insignia.
The investigation found widespread use of emission controls in cars that pump recycled exhaust gas into the engine to cool it down, producing less nitrogen oxide. However, the “exhaust gas recirculation” system failed to work properly in cold weather because of moisture build-up, meaning it was automatically shut down to avoid engine wear and tear. This led to far higher emissions levels on the road than in lab conditions.
Robert Goodwill, the roads minister, said: “They’ve not done anything illegal but what’s been disappointing is that levels of non-compliance have been higher than we had expected.”
The Society of Motor Manufacturers and Traders said: “Once it is fully adopted, all car models newly approved from next year will have to pass this on-road test, as well as a more representative lab test, if they are to be put on the market.”