Thats unbelievable how poor the sensors operate. The rear sensors in both E90's I've owned have worked brilliantly.
My first reaction when reading this thread is to go straight to back to BMW and demand they check the sensor operation and if found faulty they should pay out for the damage. They surely all cant be like this? If they say "you shouldn't rely on the technology" when I'd reply with "what's the f**kin point of having them then?"
. If they cant be trusted they may as well be disconnected.
You should definitely get them checked out - before you have your next bump.
Sorry, but this kind of thing makes me mad especially when the last generation car worked perfectly.