The German Transport Ministry has asked the European Commission to investigate Fiat Chrysler Automobiles' over the potential use of illegal emission manipulation devices.
German government documents indicate that tests on the Fiat 500X, Fiat Doblo and Jeep Renegade could prove the "illegal use of a device to switch off exhaust treatment systems."
It has gone to the European Union directly because the ministry has already raised the issue with Italian authorities, but Germany claims the accusation was dismissed and the Italians did not investigate.
The commission has said that it is the responsibility of the Italian authorities to address any wrongdoing, but said it would help Germany find a solution if needed.
"It is first and foremost a dialogue between the two member states concerned, with an obligation to keep the Commission informed and the possibility for the commission to facilitate a solution if no agreement can be found," the commission said in a statement.
A Fiat spokeswoman said yesterday that the company's cars comply with current emissions rules and do not contain defeat devices. A source at the Italian infrastructure ministry told Reuters that Italy had not received any communication from the German government on the matter.
The news comes as Germany conducts investigations into exhaust emissions in the wake of last year's Dieselgate scandal. This was the discovery that Volkswagen had been using devices on its diesel cars to trick emissions testing software into thinking it was polluting less than it really was.