General Motors' Opel unit suffered a partial setback on Friday in its attempt to fend off emissions-cheating allegations, after a German court found some of its advertising claims to be misleading to customers and therefore inadmissable.
A court in the city of Darmstadt found that two of the emissions-related advertising claims that Deutsche Umwelthilfe (DUH) environmentalist group had sought to be enjoined have to be withdrawn within four weeks, or Opel will face a fine.
The carmaker, which was also ordered to cover 60 per cent of the costs accrued by the court, already agreed to withdraw two other advertising claims in advance of Friday's hearing. Four others were deemed admissible by the court.
The case is a result of a joint investigation by DUH, news magazine Der Spiegel and public broadcaster ARD, which found that engine software Opel installed in some models breaches emissions regulations.
The DUH injunction request was filed "on account of the false performance promises made with regard to exhaust gas treatment and, thus, the deception and injury of tens of thousands of customers," said Juergen Resch, the head of the group.
The investigation found that Opel's Zafira compact vans and Insignia sedans cut off emissions control under certain conditions, including driving speed exceeding 145 kilometres per hour and temperatures below 17 and above 33 degrees celsius.
Opel is one of several companies that have come under fire in the wake of revelations that Volkswagen - Europe's biggest carmaker - equipped cars with engine-control software that turns off emissions controls when it detects a test is being conducted.