Had this bar:-
http://www.witter-towbars.co.uk/prod...gDate=16/03/12
fitted by an independent specialist as BMW wanted over $1200 to fit one with 13 pin electrics. They are readily available on ebay by sellers who will dispatch to the US. When the tow hitch is remove there is almost no indication it is there as the power socket swivels out of the way behind the bumper.