Mercedes-Benz is facing a potential High Court action brought by thousands of motorists over “defeat devices” which were allegedly installed in the manufacturer’s diesel vehicles to “cheat” emissions tests.

Two law firms behind a similar group action against Volkswagen, which was brought in the aftermath of the “dieselgate” emissions scandal, are investigating the possibility of legal action against Mercedes.

In April, around 90,000 motorists who bought or leased VW, Audi, Seat and Skoda diesel vehicles won the first round of their legal battle after the High Court ruled Volkswagen installed unlawful “defeat devices” in thousands of its diesel vehicles.

Mr Justice Waksman described the software function which allowed Volkswagen vehicles to “artificially” pass EU emissions tests as a “fundamental subversion of the test and the objective behind it”.

Volkswagen – which “maintains that because customers have not suffered any loss, it does not owe them compensation” – is currently pursuing an appeal against that ruling at the Court of Appeal.

Slater and Gordon and Leigh Day are now preparing a case against Mercedes over vehicles featuring its AdBlue technology, which the manufacturer claimed would reduce nitrogen oxide (NOx) emissions to create “our cleanest diesel cars ever”.

The firms say that more than 80,000 people in the UK who own AdBlue vehicles, which they claim contain unlawful “defeat devices”, could join the group claim against Mercedes.

In a statement, Karolina Kupczyk, of Slater and Gordon, said: “There is overwhelming evidence that Mercedes sold highly polluting vehicles which did not comply with regulations intended to reduce emissions of dangerous NOx emissions.

“Customers who bought affected models may have a claim for compensation against Mercedes. We intend to hold this carmaker to account for deceiving the car-buying public.

“Anyone eligible should join the group action to show these big corporations that they are not above the law.

“Mercedes traded heavily on the image of being green, environmentally friendly and producing efficient diesel cars. We can now see that customers and regulators have been deceived.

“It is likely that customers have overpaid for their non-compliant vehicles and the resale value will be affected, therefore we believe that customers are entitled to financial compensation.”

Bozena Michalowska Howells, a solicitor with Leigh Day, said: “We have already been approached by Mercedes owners who have received a letter from Mercedes-Benz recalling their vehicle, drivers who had specifically chosen 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.”

A spokeswoman for Mercedes’ parent company Daimler said: “We believe that the claims are without merit and will vigorously defend against any group action.”