I recall from when the E70 came out that it was up to 500 lbs heavier than the E53, depending on options.

While GVWR and GAWR are legally defined numbers, based on the manufacturer's rating, the concept of GCWR is less clear. It is a commercial vehicle term, not a passenger vehicle term, in many cases. Some jurisdictions don't define it at all. I would agree that it is generally GVWR of the tow vehicle, plus a trailer figure, but the trailer figure can be either the GVWR of the trailer, or an arbitrary number that the tow vehicle manufacturer specifies as a tow limit. That last one is the confusing one, since there are not standards for measuring it that are in common use (but SAE is getting there now, it is just that vehicle manufacturers aren't using the SAE standard)

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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