On a personal note my 2013 VW Golf TDI recently became due for it's California smog test. Passed with no problem. Just hooked up the diagnostic port to the tester machine which read the emissions from the ECU and sent the results to the state. The tech and I had a good laugh. We were pretty sure that the VW engineers would make a cheat that would work. They're pretty good you know. See you next year.