The 2015 Audi A8. (credit: Audi)

Over the weekend, Volkswagen Group and its luxury brand Audi confirmed that certain Audi models are currently under investigation by US and European authorities, apparently for irregularities involving emissions numbers from gas- and diesel-powered automatic transmission vehicles.

Last week, the German magazine Bild Am Sontag reported that California’s Air Resources Board (CARB) had discovered emissions irregularities on unspecified Audi models separate from the diesel scandal that has wracked VW, Audi, and Porsche brands. Neither VW Group nor CARB confirmed the reports to any outlet, but Audi said that it would “continue to work with regulators.”

This fresh wrinkle in VW Group’s plans appears to be related to how certain Audi vehicles respond when the steering wheel is never moved more than 15 degrees during a drive. If the steering wheel hardly moves, the car assumes it’s undergoing a treadmill test and seemingly curtails carbon dioxide (CO₂) emissions. According to a source speaking to The Wall Street Journal, as well as an internal Audi document the paper obtained, “Audi engineered the automatic transmissions to run at very low RPMs during treadmill tests to pass emissions tests, but then to run at full performance on the road, resulting in higher greenhouse gas emissions.”