Mercedes-Benz went on trial on Tuesday in a class action-style lawsuit which alleges that the German carmaker knowingly manipulated diesel-emissions tests by installing defeat devices.

Germany’s largest consumer protection group, the VZBZ, accused the carmaker of installing devices in its GLK and GLC SUV models that in tests made it appear the vehicles produced lower pollutant levels than they actually did in traffic.
The crux of the case before the Stuttgart court is whether Mercedes-Benz knowingly deceived customers by controlling the purification of exhaust gas, thus meriting claims for damages.

The lawsuit seeks to set a precedent that would enable owners of Mercedes GLC and GLK cars to gain compensation for software that was allegedly used to trick emissions tests.

The lawsuit covers nearly 50,000 GLC and GLK models and was made possible after Germany passed a law in 2018 that allowed consumer protection organisations to litigate on behalf of the consumers they represent, avoiding the high legal costs that could discourage people from bringing legal action.

Mercedes-Benz said the claims by diesel customers as well as the lawsuit were unfounded. Over 25,000 such claims have been brought before courts, 95% of which have failed, it said.

The matter is part of the wider ‘Dieselgate’ emissions scandal that has cost rival Volkswagen (VOWG_p.DE) billions of euros in vehicle refits, fines and legal costs.