Vehicles from a host of major car manufacturers did not contain devices alleged to have allowed them to cheat on emissions tests, a judge at the High Court has ruled.
More than a dozen manufacturers are being sued by around 1.6 million motorists over claims that several diesel vehicles made from 2009 onwards contained “prohibited defeat devices” (PDDs).
The cases involved 20 “sample vehicles” made by five manufacturers: Mercedes-Benz, Renault, Nissan, Ford, and Peugeot and Citroen.
The 880,000 motorists claimed they had been misled about emissions tests.
The ten-week trial concluded in March and, in a 369-page ruling handed down today, Lady Justice Cockerill said most of the strategies did not constitute PDDs, with the exception of one in Mercedes cars that was removed in 2015, and another used in some Peugeot-Citroen vehicles.
The judgement said: “The Court rejected most of the principal allegations advanced against the manufacturers whose vehicles were examined at trial.”
It added: “In the majority of instances, the Court found that the relevant strategy did not constitute a prohibited defeat device.”
Mercedes welcomed the ruling but said it disagreed with the court judgement that one of its four sample vehicles was not compliant prior to the software update.
The German carmaker said: “In our view, the emission control software functionalities are justifiable on both technical and legal grounds. We are actively considering all of our available options, including a potential appeal.”
Peugeot-Citroën has yet to comment.
Those taking legal action either bought, leased or otherwise acquired a diesel vehicle made by one of the companies, with most living in England and Wales.
Barristers for the motorists told the trial the devices installed in the cars allowed the vehicles to detect when they were being tested and alter the amount of harmful emissions produced so they fell within emissions regulations.
However, the court found that not every calibration or emissions-control strategy amounted to a defeat device.
“For a defeat device to be found, there needs to be an intention to cause the emissions control system to operate differently when it senses it is being tested,” the judge found.
“It was not enough for the Claimants simply to establish that the challenged strategies reduced the effectiveness of emissions-control systems outside the relevant testing conditions.”
Solicitors for the claimants did note that Justice Cockerill said “if an alternative approach to the meaning of ‘defeat device’ were taken, a larger number of devices would be established, including devices in each of the lead manufacturers cars”.
James Oldnall, managing partner at Milberg, which represented some of the claimants, said: “We are pleased that the court has ruled that Mercedes installed illegal defeat devices, just like Volkswagen back in 2015.
“The fight is not over on this case, but the first domino has fallen. We are on the right path and will continue pushing to hold these carmakers to account.”
A further trial is also scheduled for October this year to determine the consequences of any actionable breaches and any issues relating to damages or other remedies.
This case only examined 20 sample vehicles made by Mercedes-Benz, Renault, Nissan, Ford, and Peugeot and Citroen. The wider case also involves models made by Opel and Vauxhall, Volkswagen and Porsche, Jaguar Land Rover, BMW, FCA and Suzuki, Volvo, Hyundai-Kia, Toyota and Mazda.
The dieselgate scandal first emerged in September 2015, when the US Environmental Protection Agency accused Volkswagen of installing software – which became known as “defeat devices” – on diesel cars to lower readings of the cars’ nitrogen oxide emissions.
This software recognised when cars were undergoing official emissions tests, and turned on systems designed to reduce their output of nitrogen dioxide, a gas which can cause respiratory problems.
But when the cars were used on the road, the systems were turned off, in order to improve performance. The net result was that cars produced significantly higher levels of pollution in everyday use than official figures suggested.
VW later admitted the defeat devices had been used deliberately to circumvent emissions tests in the US, and had been fitted to some 11 million cars worldwide.
It has paid out some £27.8bn worldwide in fines and compensation over the scandal, mostly in the US. That includes £193m paid to 91,000 British motorists.
As part of the High Court trial in London, barristers for the car owners cited a report from the Centre for Research on Energy and Clean Air.
It found that excess nitrogen oxide – the emission created by diesel engines – had caused 124,000 premature deaths and 98,000 new cases of asthma in children in the UK and Europe between 2009 and 2024.
