20:05 11-07-2026

UK Diesel Trial: Judge Sides Mostly With Carmakers, but Appeals and a Damages Stage Loom

London’s High Court dismissed most core claims against Mercedes-Benz, Ford, Nissan, Renault, Peugeot and Citroen, but the diesel dispute is far from over.

The British diesel case that could have become a new Dieselgate is, for now, tilting in the carmakers’ favour. London’s High Court dismissed most of the principal allegations against Mercedes-Benz, Ford, Nissan, Renault, Peugeot and Citroen — but it didn’t close the case entirely: appeals are possible, and a separate stage on consequences and compensation begins this autumn.

The dispute centres on so-called defeat devices — devices or algorithms that can make an emissions-cleaning system behave differently during a test than in real-world driving. Judge Sara Cockerill adopted a narrower reading: in her view, the ban covers specifically decisions that intentionally or impermissibly change how the system operates when it detects a test cycle. That distinction matters for manufacturers — if emissions-control logic depends on temperature, combustion mode or engine-protection conditions, it’s easier to defend as a technical necessity rather than as deception.

The ruling can’t be called a clean sweep for the carmakers, either. The court made adverse findings on a device tied to coolant temperature in some Mercedes-Benz cars, as well as on a combustion mode used in certain Peugeot and Citroen vehicles. Mercedes-Benz and Stellantis have already said they’re considering an appeal. Claimants’ lawyers, for their part, argue the court took a narrower approach than courts elsewhere in Europe.

The scale of the case is enormous: around 1.6 million claimants, 13 group actions, and roughly 800,000 similar claims that could be affected by this ruling. For diesel owners, the main challenge now isn’t just proving elevated emissions — it’s showing that a specific system was an unlawful way of gaming the tests. That’s a higher bar than after the Volkswagen scandal, where a test-recognition scheme was proven outright.

Diesel litigation is looking less like a battle of slogans and more like a dispute between engineers, lawyers and owners over every line of an engine-management algorithm.