Well, I went to the garage and checked the VIN on the car with the one on the smog test report and it matches. I guess I'll see what happens in two years. I did look at all the older test reports and they all indicate a six cylinder so I think this was a "Fat Finger" error. Regardless I'm just happy to have passed the test. The effort and expense I had to go through smogging my 944 Turbo was enough to make me consider not fixing the A/C on the 190E last summer.