Chrysler: PT Cruiser no farter

"All Mercedes and Chrysler models fulfil the legal emissions requirements," a Mercedes-Benz spokeswoman said, while a Chrysler spokesman had no immediate comment.

Germany's Federal Environmental Agency said its tests had shown catalytic converters on some models including the Chrysler PT Cruiser did not operate properly when the cars accelerated at speeds above 120 km/h.

"The PT Cruiser's carbon monoxide emissions are unacceptably high," agency official Falk Heinen said. He added: "The company has informed us that it does not intend to change its engine controls for economic reasons."

The Mercedes spokeswoman said that emissions tests at speeds above 120 km/h were not part of the process to get cars certified, but Heinen disputed this, insisting pollution limits had to be adhered to at any speed.

"Chrysler's behaviour is not acceptable from a legal perspective," he said.