[Lyle O]

Driver air bags are to always deploy in a crash, regardless if seat belts are buckled or someone is sitting in the seat. Passenger bags will depend usually on seat sensors indicating if there is someone there. Most cars have seatbelt pretensioners also (Porsches certainly do), and they activate to take up the slack at moment of impact, so that they actually work in a crash. Even in high speed crashes (120 mph), these systems are surprisingly effective, with deployment possible in just a few milliseconds. There are multiple accereation sensors throughout the car, but most are biased toward front end crash events. In this case, if the car went sideways at very high speed (as the wreckage would indicate), there is no possible system to mitigate the situation. I worked on the development of the earlier airbag sensor systems (both mechanical and piezo), and, as we used to say, you can't beat the laws of physics.