“The vehicle has all sorts of sensors (pitch, yaw, lateral and longitudinal acceleration, and deceleration, etc.) that allow it to understand its orientation, so it knows when it’s on an incline,” explained a BMW spokesperson. “It’s likely a catchall, every-worst-case-no-matter-how-unlikely scenario safety precaution to try to prevent any chance of the vehicle moving should the programming be interrupted or go wrong.”
Basically, BMW doesn’t want to put the owner in a risky situation. While unlikely, anything can happen, and if the parking brake were – for some reason – to disengage, the vehicle would be on flat ground and not rollaway at high speed. Interestingly, there are other prerequisites for a BMW software update.
The automaker stipulates that the battery charge level should be sufficient, the transmission must be in park gear, and the engine (if it’s an ICE vehicle) needs to be switched off.