UK High Court Rejects Most Diesel Emissions Claims Against Five Carmakers

A high court judge ruled that most emissions-control strategies used in 20 diesel models sold by five manufacturers did not constitute prohibited defeat devices. The 15-week trial examined vehicles from Mercedes, Ford, Renault, Nissan and Peugeot-Citroën produced from 2009 onward.

The claimants argued that software reduced nitrogen oxide emissions during tests compared with normal driving conditions.

Cockerill stated that proving an intention to rig tests was required and that the majority of strategies examined did not meet the legal definition of a defeat device. The ruling also binds other manufacturers not named in the case. The judge found that technology in some Mercedes and Peugeot-Citroën vehicles could qualify as defeat devices.

She noted that testing data was difficult to interpret and that alternative legal interpretations could have identified more devices.

Mercedes-Benz said the court ruled largely in its favor but is considering an appeal on one non-compliant vehicle. Stellantis, owner of Peugeot-Citroën, is also weighing an appeal. Nissan stated its vehicles did not contain defeat devices. Renault said its cars complied with all applicable regulations.

Ford did not respond to requests for comment. Lawyers for the claimants described the ruling as disappointing and said they are considering an appeal. They noted the judgment creates a divergence between UK and EU interpretations of defeat-device rules.

The case is the largest group action trial in English legal history and follows the 2015 Volkswagen emissions scandal by more than a decade.