It's been 15 months since news broke that VW Group had used "defeat device" software in its diesel cars and SUVs that let them emit far more than permitted levels of nitrogen oxides in real-world use.
Even now, however, the Volkswagen diesel scandal continues to grow new tentacles as investigators uncover additional apparent instances of wrongdoing.
Last month, California regulators reportedly found software in an automatic transmission used by Audi that lowered emissions during testing, this time in both gasoline and diesel cars.
That additional use of defeat software has now apparently enmeshed Porsche as well, one of the most profitable brands within the sprawling VW Group.
According to an article in the German magazine WirtschaftsWoche, sources inside Porsche tipped off the German transport ministry to the alleged cheating.
The report didn't indicate which components had their performance changed by the software, according to a report by Bloomberg last Thursday.
2015 Porsche Cayenne Diesel
The "defeat device" software apparently lowered carbon emissions from gasoline cars by calculating how much the steering wheel was being turned.
Until now, Porsche's only involvement in the scandal came in the handful of models to which it fitted Audi 3.0-liter V-6 diesel engines in Europe. Only one of those (the Cayenne Diesel SUV) was sold in North America.
A final settlement has been signed for almost half a million Audi and Volkswagen cars that used various 2.0-liter diesel 4-cylinder engines from 2009 through 2015.
But a similar settlement for the separate vehicles from Porsche, Audi, and Volkswagen fitted with the V-6 diesel has yet to be released.
How it worked
During tests on a dynamometer, or rolling road, a car being tested for its emissions has no inputs to the steering.
Reportedly, the Audi transmission being investigated only switched to a regular mode with higher CO2 emissions if the steering wheel was turned more than 15 degrees, as it would be during regular on-road driving.
2016 Audi S8 4-door Sedan Plus Grille
Germany's Bild am Sonntag claimed that Audi ended its use of the transmission-linked defeat-device software in May 2016.
The powerful California Air Resources Board reportedly identified the software in an Audi vehicle built prior to that month.
Porsche responded to questions about that technology by saying that software to detect steering movements is used to improve the car’s performance when driving, and is not related to emissions testing.
The company told Bloomberg it is cooperating fully with the investigation.