UK High Court rules in favor of major carmakers in diesel emissions case

On 10 July 2026, Justice Sara Cockerill of the UK High Court delivered a judgment that largely rejected the diesel‑emissions cheating claims brought by about 1.6 million motorists against five major manufacturers – Mercedes‑Benz, Ford, Peugeot‑Citroën, Renault and Nissan. The court held that a “defeat device” must be designed to change emissions‑control performance specifically for test cycles, and found the majority of the allegations did not meet this definition.

The trial examined 20 sample vehicles produced between 2012 and 2017. The court identified adverse findings in a coolant‑temperature device used in some Mercedes cars (already removed by a software update) and certain technical strategies employed by Peugeot‑Citroën, but concluded that most claims failed. The ruling will also apply to roughly 800,000 similar claims against other carmakers and sets the stage for a second trial in October to determine the amount of damages.

The case follows the 2015 Volkswagen “Dieselgate” scandal, which saw the German automaker pay more than €32 billion in penalties worldwide. Lawyers for the claimants said they may seek permission to appeal, while the carmakers welcomed the decision.