The request, which is subject to strict confidentiality, will see Daimler AG conduct an internal investigation in association with the Department of Justice.
The firm says it will “investigate possible indications of irregularities and of course take all necessary actions”.
The matter is believed to be related to class actions taken out in February by Mercedes-Benz owners in the US. Owners of Bluetec diesel models allege that pollution control technology turns off at cooler temperatures, resulting in NOx emissions far higher than those stated in the US Clean Air Act.
Daimler insists “the class actions are considered to be without merit and Daimler will defend itself against them with all available legal means”.
The surprise news from Daimler follows Volkswagen’s confirmation it will offer to buy back almost half a million US diesel cars as part of an agreement with authorities to settle the ‘dieselgate’ issue.
It has also since emerged that Mitsubishi offices in Japan were raided by Japanese officials investigating the firm’s admission of ‘misconduct’ in testing fuel economy for some of its city car models.