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Mercedes face legal action over AdBlue emissions 'cheat device'

Law firm Leigh Day are investigating a potential group claim against the German car manufacturer Mercedes-Benz over an alleged 'cheat device'

Posted on 11 May 2020

Law firm Leigh Day are investigating a potential group claim against the German car manufacturer Mercedes-Benz over an alleged ‘cheat device’ fitted on some of their cars in order to artificially reduce emissions to pass EU Emissions tests.

The claims are being investigated on behalf of owners of Mercedes vehicles who purchased models with the AdBlue fuel options and could be worth thousands of pounds per vehicle as Daimler, who own Mercedes-Benz, face a total compensation bill of at least £65m in the UK alone.

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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.

The group claim is being investigated by law firm Leigh Day, joint-lead lawyers in the emissions litigation on behalf of UK Volkswagen owners, who recently won the first round of their emissions case against Volkswagen in the UK High Court.

Leigh Day argued that Volkswagen had deceived car owners as to the compliance of vehicles with EU Emissions Regulations. Lawyers for the UK drivers argued that Volkswagen engines contained defeat device software which sensed when the vehicle was being tested and so artificially reduced emissions in order to pass that test.

Volkswagen have always argued that the software did not meet the legal definition of a defeat device and so was not illegal. However, in April 2020 the High Court in London found that the decision by the KBA, the German road vehicle authority, that the software was a ‘defeat device’ was binding in the English High Court.

The court also agreed that the fact that the engine operates in different modes during the emissions test means that it contained a ‘defeat device’ under the EU emissions Regulations.

In June 2018 the KBA found that Daimler, the parent company of Mercedes, had also used illegal software to alter diesel emissions. It ordered Mercedes to recall affected vehicles The German Courts also concluded that Daimler have also been using a prohibited defeat device.

The purpose of AdBlue or Diesel exhaust fluid is to reduce the amount of air pollution created by a diesel engine. Specifically, it is used in selective catalytic reduction that lowers NOx concentration in the diesel exhaust emissions.

In Mercedes vehicles the control of nitrogen oxide emissions is carried out via exhaust gas recirculation (EGR). During EGR, part of the exhaust gas is fed back into the intake system of the engine and takes part in the combustion again reducing the level of NOx in the emissions. The EGR is reduced at cooler outside temperatures (the so-called ‘thermal window’).

In the Mercedes judgment the German court concluded “It is obvious that such a defeat device should not be regarded as legal by the EU legislator” (para 55) and the argument that such a ‘thermal window’ was necessary for component protection was not permissible.

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."

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