The BMW wiring kit is very straightforward. There is a connector near the spare tire waiting for the harness. The harness is led out through an existing hole (use the included grommet), and the plug receptacle c/w spring-loaded door is mounted to the drawbar. The only difficulty some have had is figuring out the BMW plug connector - there is a release lever, so to speak, and once you locate it you are pretty much there.

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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