My BMW dealer found a fix for this same issue however it was only temporary and after 6 mnths it has started to come back, albeit not as frequent as before and it's generally when the suspension is in the lowest setting. I'm just learning to live with it.

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2006 BMW X5 4.8is Lemans Blue/Beige/Dark Maple
-Nav, Comfort Seats, Heated Steering Wheel,
Rear Airbags, AUX Input
2009 BMW M3 Space Grey/Black/Carbon
-all options