The photo shows the standard hitch (realizing that you can only trust a web site so far....) BMW specifically warn against using weight-distribution hitches (which seems silly).

The Optional Equipment line shows up in the configurator as a zero cost option, only available on the diesel and V8. I think it is their way of flagging a higher tow limit in the configurator, and that it is just the transmission difference.

Still wondering why BMW Customer Relations say 6000 lbs, when a number of web sites working off a BMW press release say 6500 lbs. Doesn't seem likely that they all invented the new higher number. The press release could have been wrong, of course.

http://www.canadiandriver.com/2009/0...35d-diesel.htm

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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