Based on information from the Global website, the 4.8i and the 3.5d could potentially tow 7,700 lbs.

But here in the US, BMWNA only offers a Class III hitch which significantly limits the amount of weight tolerances when towing.

Looking in the market for other competitors AWD 7-seaters towing capacities, I found:

The Mercedez Benz GL320 offers 7,700 lb capacity.

The Audi Q7 pulls 6600 lbs.

As this is supposed to be a UTILITY vehicle, which for me, means a car I can use to carry a big family with cargo (7 seater), run long commutes (diesel), drive in the winter (AWD and higher ground clearance), and tow a heavy trailer (enclosed car trailer), I'm affraid I'll have to look somewhere else.

Shame. Because it's all down to an optional hitch, not the vehicle itself.