Millions of UK drivers have broadly lost the initial stage of a High Court battle over allegations that carmakers used prohibited defeat devices (PDDs) in diesel vehicles. The ruling, delivered Friday by Lady Justice Cockerill, found that most of the strategies employed by over a dozen manufacturers did not constitute PDDs.
More than 1.6 million UK drivers accused carmakers of using devices in diesel models produced from 2009 onwards to cheat official emissions tests. The vehicles in question were manufactured by Mercedes-Benz, Opel and Vauxhall, Nissan and Renault, Volkswagen and Porsche, Peugeot and Citroën, Jaguar Land Rover, Ford, BMW, FCA and Suzuki, Volvo, Hyundai-Kia, Toyota, and Mazda. The 13-week trial, which began in October, focused on evidence against 20 sample vehicles from five manufacturers: Mercedes-Benz, Renault, Nissan, Ford, and Peugeot and Citroën. The remaining manufacturers are bound by Friday's ruling.
Motorists' barristers argued that the devices detected when vehicles were being tested and altered harmful emissions to fall within regulatory limits. This, they claimed, allowed cars to pass tests with higher actual outputs, constituting a breach of contract. However, in a 369-page ruling, Lady Justice Cockerill stated that most alleged PDDs did not succeed.
Exceptions were noted for one device in Mercedes cars, which was removed in 2015, and another used in some Peugeot-Citroën vehicles. For Ford, Renault, and Nissan, the judge ruled that the devices did not meet the definition of a PDD and therefore did not breach emissions regulations.
Leigh Day Solicitors, representing the drivers, stated that the judgment creates a "significant divergence between the legal position in Great Britain and much of Europe." The firm acknowledged some favorable findings but expressed disappointment with parts of the decision, particularly regarding its impact on environmental and consumer protection. Lawyers for the vehicle owners are considering an appeal.
All five manufacturers contested the claims, asserting that their emissions control strategies were appropriate. Lawyers for Nissan called the case "fundamentally misconceived," while Renault's barristers described the claimants as "PDD hunting."
This case followed a 2020 High Court ruling that found Volkswagen had installed unlawful defeat devices, a scandal known as 'Dieselgate.' Lady Justice Cockerill noted that no allegation was made that any of the sample vehicles contained a PDD identical to those used by Volkswagen.
The case centered on harmful nitrogen oxides (NOx) emissions. Campaign group Mums for Lungs called the judgment "bizarre" and "occasionally contradictory," stating the court took a "very narrow definition of a diesel defeat device."
BMW, Vauxhall, Ford, and Renault/Nissan represent the manufacturers facing the largest numbers of claimants. A further hearing in the case is scheduled for October.