High Court Finds Most Major Car Manufacturers Did Not Use Emissions-Cheating Devices
Vehicles from numerous leading car manufacturers were found not to contain devices alleged to have enabled cheating on emissions tests, according to a ruling by a judge at the High Court.
Over 1.6 million motorists are suing more than a dozen manufacturers, claiming that several diesel vehicles produced from 2009 onwards contained "prohibited defeat devices" (PDDs).
The legal cases involved 20 "sample vehicles" from five manufacturers: Mercedes-Benz, Renault, Nissan, Ford, and Peugeot and Citroën.
Approximately 880,000 motorists asserted they were misled regarding emissions tests.
The ten-week trial concluded in March, and in a 369-page judgment delivered today, Lady Justice Cockerill stated that most of the strategies examined did not constitute PDDs, except for one strategy in Mercedes cars that was removed in 2015, and another used in some Peugeot-Citroën vehicles.
"The Court rejected most of the principal allegations advanced against the manufacturers whose vehicles were examined at trial."
"In the majority of instances, the Court found that the relevant strategy did not constitute a prohibited defeat device."
Mercedes welcomed the ruling but disagreed with the court's finding that one of its four sample vehicles was non-compliant prior to the software update.
The German automaker stated,
"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 not yet issued a comment.
The claimants either purchased, leased, or otherwise acquired diesel vehicles from the involved companies, with most residing in England and Wales.
Barristers representing the motorists argued that the devices installed in the vehicles allowed them to detect when emissions tests were being conducted and adjust harmful emissions output to comply with regulations.
However, the court determined that not every calibration or emissions-control strategy qualifies as 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 stated.
"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 noted that Justice Cockerill remarked,
"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, representing some claimants, said,
"We are pleased that the court has ruled that Mercedes installed illegal defeat devices, just like Volkswagen.
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 scheduled for October this year to determine the consequences of any actionable breaches and issues related to damages or other remedies.
This case examined only 20 sample vehicles from Mercedes-Benz, Renault, Nissan, Ford, and Peugeot and Citroën. The broader case also involves models from Opel and Vauxhall, Volkswagen and Porsche, Jaguar Land Rover, BMW, FCA and Suzuki, Volvo, Hyundai-Kia, Toyota, and Mazda.
Background of the Dieselgate Scandal
The dieselgate scandal first surfaced in September 2015 when the US Environmental Protection Agency accused Volkswagen of installing software—known as "defeat devices"—on diesel cars to reduce reported nitrogen oxide emissions during official tests.
This software detected when cars were undergoing emissions testing and activated systems to lower nitrogen dioxide output, a gas linked to respiratory issues.
However, these systems were deactivated during normal driving to enhance performance, resulting in significantly higher pollution levels than official figures indicated.
Volkswagen later admitted to deliberately fitting defeat devices on approximately 11 million cars worldwide.
The company has paid around £27.8 billion globally in fines and compensation related to the scandal, primarily in the US, including £193 million to 91,000 British motorists.
Health Impact and Research Findings
During the High Court trial in London, barristers for car owners referenced a report from the Centre for Research on Energy and Clean Air.
The report found that excess nitrogen oxide emissions from diesel engines caused 124,000 premature deaths and 98,000 new asthma cases in children across the UK and Europe between 2009 and 2024.
