Could be a number of things - bearings or differential in the rear axle worn or out of oil, tyre wear, or maybe the mother-in-law in the boot!
The 2007 BMW X3 has 55.0 in. of rear shoulder room.
The 2007 BMW X5 has 36.6 in. of rear leg room.
The 2007 BMW M6 has 30.1 in. of rear leg room.
The 2007 BMW M5 has 57.2 in. of rear shoulder room.
The 2007 BMW X3 has 35.8 in. of rear leg room.
The 2007 BMW M5 has 37.8 in. of rear head room.
The 2007 BMW M5 has 36.0 in. of rear leg room.
The 2007 BMW M6 has 49.4 in. of rear shoulder room.
The 2007 BMW X5 has 39.0 in. of rear head room.
The 2007 BMW X5 has 58.0 in. of rear shoulder room.
The 2007 BMW M6 has 35.6 in. of rear head room.
The 2007 BMW X3 has 37.8 in. of rear head room.