The lawsuit filed in the US District Court of New Jersey on Tuesday accused BMW of emissions cheating on diesel vehicles, including the carmaker's X5 and 335d models.

"BMW's representations were misleading for failure to disclose emissions manipulations," the suit said. It was filed by law firms Steve W Berman from Hagens Berman Sobol Shapiro LLP and James E. Cecchi.

BMW's X5 model built between 2009 and 2013, and the 335d model which was sold between 2009 and 2011 emitted levels of nitrogen oxide "many times higher than their gasoline counterparts," the suit alleged.

'Joining the likes of Volkswagen'

It added that the vehicles' promised power, fuel economy and efficiency were obtained only be turning off or turning down emissions controls when the software in those vehicles sensed that the cars in question were not in an emissions testing environment.

"Why did BMW go out of its way to tout the environmental friendliness of these cars," Steve Berman, managing partner of Hagens Berman, asked. "Because it knew that doing so would accelerate sales. Instead of making good on those promises of protecting the environment, BMW chose to join the likes of Volkswagen and so many others to build an illegal emissions-cheating system."

BMW had emphasized in the past that it had never used any illegal defeat devices to manipulate emissions tests.

Shares in the German carmaker reduced earlier gains sharply, with traders pointing to a Bloomberg report saying that the Munich-based auto manufacturer was being sued for emissions cheating in the US.

hg/jd (Reuters, dpa)