Yup, I had the same low speed groan while the car is still cold. I got the diff oil changed and everything is fine now. There is a STB out for it. The dealer should know about the problem.
2002 M3 Titanium Silver Imola Red Interior
Solaris InvisiBulbs / Painted reflectors / Keyhole delete / Xenon Interior Lighting / PIAA Xtreme White fogs / 32% Tint / DIY Clutch stop / Blitzsafe Aux input / Umnitza Angel Eyes / UUC Evo III SSK with DSSR / Axis Deluxe Plus pads / ACS style Racing strut bar / Eibach Sportline springs / Volk Racing LE-37T wheels / Toyo T1-S 245/35F 275/30R