One problem related to differential unit has been reported for the 2007 BMW 328. The most recently reported issues are listed below.
When I start a trip my car makes an strong noise on the back. I'm pretty sure it comes from the rear differential axle-final drive assy. My car has 123206 milles. I usually make any maintenance on time. I'm really worry about this strong noise, cause this car is driving everyday by my wife with our baby inside.