[Bi When I got in my 2011 328i there was a loud sound coming from the rear speaker, sounding much like a Geiger Counter (I hadn't even started the car yet). The very annoying sound continued for the 20 min. drive home with the radio on or off. I hosed off the car off since it was dirty from being parked under a tree during a hard rain. After I hosed it the sound stopped. I hope it doesn't come back.