For what it is worth, my 2003 X5 3.0 experienced a failed wheel bearing at approximately 50,000 km (from memory). It was just within the warranty period. It had been parked at the airport for 6 days, and was totally quiet up to that point. Driving out of the airport, I heard what I would describe as a "ruh, ruh, ruh" noise, which I think is very similar to what Oil Burner described. It was a very typical wheel bearing noise, and varied with road speed and not engine speed. It didn't vary with road surface, didn't vary with turns, and was loud enough that I wondered about my chances of making it 80 km to my home. I stopped at my dealer (with no appointment) on the way home, described the problem, and suggested it was probably the LF. A tech drove it, returned in 3 minutes, and confirmed my self-diagnosis. They took it in immediately, and it was ready the next day. Loaner car and all. Great service. Anyway, the way mine failed (and they are known to fail...) it wouldn't have gone for 20,000 miles or kilometers.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue