Apparently, the software only checks if the steering wheel is being moved. If the car is being tested on a platform and the steering never moves, "clean mode" i

Apparently, the software only checks if the steering wheel is being moved. If the car is being tested on a platform and the steering never moves, "clean mode" is engaged; if driving on a road, "Enough-emissions-to-choke-a-Humvee mode" is enabled.