The claims are being investigated on behalf of owners of Mercedes vehicles who purchased models with the AdBlue fuel options and could be worth up to between £10,000 to £20,000 for each driver as Daimler, which owns Mercedes-Benz, face a total compensation bill of at least £65m in the UK alone.

Mercedes advertised AdBlue as a way of reducing emissions, promising their ‘cleanest diesel cars ever’. It is estimated that over 84,000 drivers in the UK own AdBlue vehicles and could join the group claim against Mercedes-Benz.

In June 2018, the KBA, the German road vehicle authority, found that Daimler had used illegal software to alter diesel emissions. It ordered Mercedes to recall affected vehicles. The German courts also concluded that Daimler has also been using a prohibited defeat device.

Bozena Michalowska Howells, the lawyer at Leigh Day leading the investigation into a group claim, said: “We have already been approached by Mercedes owners who have received a letter from Mercedes-Benz recalling their vehicle, drivers who had specifically chose an AdBlue model because of the low emissions promised by the advertising.

“It now seems that the promise of ‘cleaner’ diesel using AdBlue technology does not stand up to scrutiny. We believe that vehicle manufacturers should not get away with the prohibited practice of using defeat devices which allows them to trick regulators and consumers across the globe in order to increase or maintain their sale volumes, whilst their vehicles pump out much higher levels of harmful NOx gases than they have advertised.”