Dieselgate returns? Car brands in court over diesel emissions allegations

Just over a decade on from the start of the original Dieselgate emissions scandal, car brands are once again taking the stand over claims regarding the use of so-called emissions test ‘defeat devices’.

On Monday October 13 at the High Court, representatives from five car manufacturers – Ford, Citroen/Peugeot, Mercedes-Benz, Nissan and Renault – began their defence for a lawsuit in which prosecutors accuse them of manipulating official emissions tests by installing specialised devices in their cars. Such devices can alter a car’s performance, such as by limiting power, in order to provide increased fuel economy and lower emissions under test conditions.

All five manufacturers deny wrongdoing, while 220,000 car owners have accused them of being misleading and it’s thought that the scandal could potentially involve as many as 1.6 million vehicles. The brands involved in this case are in addition to a further nine manufacturers who are currently under fire for similar claims.

The trial has only just begun and a verdict is not expected until autumn 2026. It’s also possible that things could be settled out of court; in 2022 Volkswagen decided to settle after it was taken to court two years prior over claims surrounding the use of defeat devices and ended up paying roughly £193 million in compensation to 91,000 British motorists.

In a statement ahead of the trial’s commencement on Monday, senior partner at Leigh day (one of the several law firms participating in the trial), Martyn Day, said: “A decade after the Dieselgate scandal first came to light, 1.6 million UK motorists now get their chance to establish at trial whether their vehicles contained technology designed to cheat emissions tests.”

“Fourteen of the biggest car manufacturers operating in the UK are facing these claims which, if proven, would demonstrate one of the most egregious breaches of corporate trust in modern times,” Day continued.

In the meantime, YouGov polling suggests that roughly two-in-three people do not trust car manufacturers to tell the truth about emissions or environmental impacts of their vehicles, with 69 per cent saying it’s unacceptable that cars potentially with defeat devices are still being driven on UK roads.

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