Carmakers win Dieselgate 2.0: judge crushes possibility of payouts in landmark ruling
The High Court did not find evidence of the usage of cheat devices, bar a couple of small exceptions, dashing hopes of compensation for drivers

Around 1.6 million motorists have been denied a share of what could have been £6 billion in payouts following a landmark High Court ruling. The Pan-NOx Emissions Group litigation – often referred to as ‘Dieselgate 2.0’ – has ended in favour of car manufacturers as claimants failed to prove that they had been lied to over real-world tailpipe emissions.
The ruling signals the conclusion of a long-running legal battle between consumers and an array of major car manufacturers including Mercedes-Benz, Ford, Nissan and Peugeot-Citroen (now part of the Stellantis conglomerate).
The case surrounded the alleged usage of thermal windows – software used to protect and prevent a build-up of condensation inside the engine – as cheat devices to help diesel cars pass emissions tests. Claimants say they were missold a product under the false pretence that it was a ‘clean’ car, only for it to emit more nitrogen-oxide during normal driving than claimed.
However, after having tested 20 sample vehicles manufactured between 2012 and 2017, the High Court “rejected most of the principal allegations advanced against the manufacturers whose vehicles were examined at trial”.
Referencing the usage of thermal windows, the court remarked that “not every calibration or emissions-control strategy amounts to a defeat device”. The Rt Honourable Lady Justice Cockerill, the presiding judge, also conceded that there is no obligation to meet emissions regulations outside the designated test cycle and while defeat devices are illegal, simply adjusting engine performance to protect it from damage does not constitute as such.
That said, the investigation did highlight how certain instances could be identified as cheat devices – namely coolant temperature setpoint and split-injection software found in some older Mercedes and Peugeot-Citroen models, respectively. The court also pointed out that if a different definition of defeat devices was adopted, many more instances would have been deemed illegal.
Reacting to the judgement, a spokesperson for Mercedes-Benz said the brand “welcome[s]” the verdict. However, the firm says it disagrees with the court’s findings regarding the aforementioned coolant temperature setpoint, with this issue having been originally remedied by a 2015 software update. “In our view, the emission control software functionalities are justifiable on both technical and legal grounds,” the German brand said. “We are actively considering all of our available options, including a potential appeal.”
Yet another trial will take place in October this year in order to determine the consequences of any breaches – such as those by Mercedes and Peugeot-Citroen – including whether compensation is due for the limited number affected.
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