Berlin - German environmental lobby group DUH stepped up its campaign against motor industry pollution on Tuesday, accusing Fiat’s 500X compact SUV of releasing excessive levels of toxic diesel emissions.

DUH has already accused Opel, Renault and Mercedes-Benz of violating emissions levels. At a press conference in Berlin, DUH turned to Fiat Chrysler Automobiles (FCA).

“The extreme overruns of NOx emissions that have meanwhile been detected with an Opel Zafira, a Renault Espace, a Mercedes C-Class and now a Fiat SUV are technically not plausible and point towards defeat devices,” campaigner Axel Friedrich said. FCA declined comment.

The carmakers deny they are acting illegally but acknowledge that some models produce higher levels of pollution when tested in conditions more akin to real-world driving than the norms set out in a specific test regime prescribed by regulators.

European lawmakers this month backed more stringent testing methods, which cut overall emissions but under some circumstances still allow a 50 percent overshoot of the legal ceiling for nitrogen oxide of 80 milligrams/kilometre...

European regulators and authorities are investigating various carmakers. But so far only Volkswagen has been accused of illegal behaviour after it admitted to using software to manipulate emissions test results in a laboratory.

FIAT NOT CHEATING THOUGH

FCA said on February 2 that its diesel vehicles do not carry defeat devices and that while emissions levels can vary depending on driving conditions, the cars' control systems operate in the same way under the same conditions, whether in a laboratory or on the road.

The carmaker added at the time that its diesel vehicles performed within the regulatory limits when inspected using the testing cycle prescribed by European law.

On Tuesday, citing tests carried out by the University of Applied Sciences in Bern, Switzerland, DUH Managing Director Juergen Resch told a news conference that a Fiat 500X, a 2015 model of the latest Euro 6 diesel generation, had released nitrogen oxide emissions that were between 11 and 22 times the legal European limits when tested with a warm engine.

The Fiat 500X released excessive emissions in all eight tests carried out with a warm engine on the dynamometer, DUH said.

The model exceeded the statutory 80 milligram limit only during two tests with a cold engine after “specific pre-conditioning”, the group said.

Friedrich is a co-founder of the Washington-based International Council on Clean Transportation (ICCT), which commissioned the original investigation that eventually led to the exposure of VW's test-rigging.