What they did was quite sophisticated. Basically what they did was have the car tell if the car was being smog tested by all four wheels turning and if the steering wheel did not turn. If it was being tested, it ran a smog complaint tune. If not, it ran a tune that was actually usable to the driver. When they got caught, and defeated this cheat software, the cars were not viable, due to the EPA tune. Don't tell anyone but real easy to put old tune back in, and it seems, not get caught. My VW has been smogged twice since that was done...