Mercedes-Benz in the US faces a class action lawsuit from the owner of Mercedes BlueTEC diesel car that accuses it of knowingly programming so-called 'clean diesel' cars to emit illegally excessive levels of nitrogen oxides.

Reuters reports that the law firm Hagens Berman – which has played a leading role in lawsuits filed against Volkswagen – filed the lawsuit in the US District Court for the District of New Jersey. Reuters noted that Daimler has repeatedly denied that it has rigged tests and said today that the lawsuit was 'unfounded'.

The Reuters report added that a spokesman said the carmaker would examine the levels [of harmful emissions] and defend itself against the suit.

The US Justice Department is suing VW for up to US$46bn for alleged violations of environmental laws in its rigged diesel emissions tests. To cheat the emissions controls, Volkswagen installed software that allowed the vehicles to detect when they were being tested on a flatbed. When the vehicles detected they were on the road, the software caused the emissions control systems to underperform or shutdown allowing the cars to emit dangerous levels of air pollution.