Claimants to challenge High Court ruling in UK Diesel emissions case
More than 1.6 million motorists, represented by Leigh Day and Pogust Goodhead, are seeking permission to appeal a July High Court judgment that cleared most carmakers in the Dieselgate lawsuit.
In the UK Dieselgate litigation, claimants representing about 1.6 million vehicle owners have filed for leave to appeal a July High Court decision that largely favored the carmakers. The original trial, held in October 2025, involved 20 manufacturers such as Mercedes, Ford, Renault and Nissan, accusing them of fitting software that reduced emissions controls during testing. Lady Justice Cockerill concluded that only three cars - two from Mercedes and one from Peugeot-Citroën - used prohibited defeat devices, with the remaining 17 deemed lawful.
Leigh Day senior partner Martyn Day and Pogust Goodhead partner Anna Varga said the judge’s interpretation of the emissions regulation was too restrictive and that key technical evidence should be revisited. Their joint appeal aims to broaden the definition of a prohibited defeat device and overturn several findings. Mercedes has reiterated that the claims lack merit and it will defend itself vigorously.
Why it matters
The outcome could reshape liability standards for automotive emissions software across Europe.
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