I think people are all over the board on when the brakes need to be serviced based on their driving conditions, climate, city vs. highway, etc. I know my e53 I think I went through pads every 30K miles and rotors not too much longer than that.

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2008 X5 4.8
Jet Black/Black Nevada/Dark Burl Walnut
Adaptive Drive
Premium Pack
Tech Pack
Climate Pack
Sport Pack
20" Wheel Option
Premium Sound
Sirius Satellite
Rear DVD Entertainment
Multi-Contour Seats
Comfort Access
3rd Row Seat
Heated Front Seats
Running Boards
3M VentureShield Paint Protection Film