FRANKFURT/WASHINGTON U.S. Environmental Protection Agency said on Monday it had not opened an official investigation into Daimler’s luxury car brand Mercedes-Benz but had only requested information to explain emissions levels in some of its cars.

A spokesman for Daimler said on Sunday it was fully cooperating with the request for information, and that Mercedes-Benz cars conformed with all rules and norms.

Daimler said the EPA request for information came in response to a class-action lawsuit filed by law firm Hagens Berman on Feb. 18, 2016, in the New Jersey District Court.

The suit accuses Mercedes of deceiving consumers with false representations of its BlueTEC vehicles, which it marketed as “the world’s cleanest and most advanced diesel.”

A Daimler spokesman said the suit was wholly unfounded and without merit.

The lawsuit alleges the automaker knowingly programmed its Clean Diesel vehicles to emit illegal, dangerous levels of nitrogen oxide, or NOx, at levels 65 times higher than those permitted by the EPA when operating in temperatures below 50 degrees F (10 C).

Daimler said its cars conformed to all relevant rules and regulations.

It said, however, that under certain circumstances, a system to treat exhaust fumes could operate at a level of reduced effectiveness to prevent condensation from building up in the exhaust system. The condensation could otherwise lead to corrosion and damage the effectiveness of the engine and exhaust system.  

That is permissible and not illegal, a spokesman said late on Sunday.

German daily Handelsblatt was first to report the EPA request for information. In its Monday edition, Handelsblatt quoted Christopher Grundler, director of the EPA’s Office of Transportation and Air Quality, as saying: “We know about the lawsuit. We have contacted Mercedes and requested the test results for the U.S. diesel engines.”

EPA spokeswoman Laura Allen confirmed Grundler’s comments.

(Reporting by Edward Taylor in Frankfurt; Additional reporting by David Shepardson in Washington; Editing by Peter Cooney, Greg Mahlich)