The company promises to "employ all legal means" to fight any allegations that it sold diesel vehicles equipped with an emissions defeat device.

Daimler has promised to fight any official allegations that it used a defeat device to cheat diesel emissions tests.The automaker would "employ all legal means" if Germany's emissions enforcement authorities officially accuse the company of equipping cars with illegal software, according to a statement to Bloomberg. The defensive tone was balanced with a promise to "continue to work constructively with authorities."

Suspicions of emissions violations surfaced in May when German prosecutors raided several Daimler offices to look for evidence in an ongoing investigation. The Stuttgart prosecutor's office also confirmed that it had contact with US authorities, though the nature of the collaboration has not been fully disclosed.

More recent reports in German media claim the inquiry has been elevated and the company stands accused of selling more than a million Mercedes-Benz cars with illegal emissions technology between 2008 and 2016.

The motor transport authority has now confirmed plans to expand its test program "just as it has done with other manufacturers in the past."

In the wake of the Volkswagen scandal, authorities in the US and abroad appear to be scrutinizing other auxiliary emissions control devices (AECDs) employed by automakers. Such systems can be used legally to disable emissions controls in certain circumstances, such as during engine warmup or at extreme temperatures, to protect sensitive equipment against premature failure. Potential abuse or misrepresentation of such systems could run afoul of the law, but without necessarily rising to the level of a 'defeat device' that detects when the vehicle is undergoing a lab test.

Daimler's troubles represent just one of several ongoing emissions investigations that span multiple countries and several automakers.