hidden winch on D3/4 with standard bumper and NO roo-bar
So when I was involved in Motorsport, we’d use three axis solid state accelerometers to plot track and g-forces etc. You’d mount it centrally to get the best accuracy. For the bags it makes sense to place an accelerometer closest to the bag in question to capture the shock pulse as soon as possible, plus the intensity at the impact point (crumple zones and substrate of the vehicle will change the wave pattern). This explains the number of sensors on the vehicle and their placement. I cannot fathom why they’re going off in car parks other than they’re not small impacts and are triggering stage 1. Saying that, it should require it to be enough for bodily impact to a vehicle surface, and 10kph isn’t that.