Most new diesel cars emit considerably more toxic emissions than is shown in official laboratory tests, a study by Europe’s largest motoring organisation has found.
Vehicles by Renault, Nissan, Hyundai, Citroen, Fiat and Volvo have all been found guilty of producing much more harmful emissions than officially declared when tested under conditions that are closer to real-life.
German automobile club Adac compared the performance of 79 different diesel cars in EU-endorsed NEDC tests with the UN-approved WLTC, which is believed to represent more realistic driving conditions. The two figures matched only in 25 per cent of cases.
Reported by the Guardian and the Independent, the comparison showed that some of the tested vehicles - including Volvo S60, Renault Espace Energy, Jeep Renegade and Nissan X-Trail - exceeded legal European limits for nitrogen oxide in the more realistic test over ten times.
"If all cars complied with [the official EU NOx limit], we would have solved all the worst health effects,” said Reinhard Kolke, head of test and technical affairs at Adac.
"Every consumer has the right to expect all manufacturers to do this. But still there are these gross emitters."
The comparison doesn’t suggest the discrepancies could be caused by any sort of cheating device similar to that at the heart of the Volkswagen 'VWgate' affair.
Spokespeople for Nissan, Renault and Hyundai all stated their companies do comply with European regulations.
German car-maker Volkswagen has been shaken by the revelations earlier this month that it used special software to cheat in emission tests.
It has been revealed that over 11 million cars equipped with the so called ‘defeat device’, which turns on emission control technology when the car is being tested, have been sold around the world.
In the UK only, there are believed to be 1.2 million vehicles manufactured by the VW group, including Volkswagens, Audis, Skodas and Seats, all fitted with the cheating software.
The German car-maker said it would contact the owners to arrange for their vehicles to be 'corrected'.
The defeat device makes the cars comply with legal emission limits only for the time of the testing. Under real driving conditions, the emissions of toxic nitrogen gases could be exceeding the legal limits by up to 40 times the accepted level.
The problem is that disabling the defeat device may lead to decreased performance or higher fuel consumption.
"We all want clean air to breathe, but motorists will understandably be worried about the MPG (miles per gallon) implications of these so-called corrections on the cars many will have bought on the strength of their fuel economy," said Steve Gooding, director of UK motoring charity RAC Foundation.
On Thursday, Volkswagen announced some 4,000 vehicles in the UK will be temporarily withdrawn from the market due to the emission cheating technology.
The firm also said it would take several months to complete the investigation into the rigging of emissions tests. Volkswagen’s supervisory board has pushed back an extraordinary general meeting scheduled for next month, but said the management would inform the public next week about possible solutions.