We too tried to tow our BMW's (an E39 5 series and a E46 3 series, both automatic transmissions), to make a long story short, if you want to take the BMW with an automatic transmission, put it on a trailer. Both the 3 and 5 series are rear wheel drive and Remco does not make a disconnect for them. We ended up changing to a Mini (with a 6 speed). Blue Ox makes a hitch for it, weight is 2500 lbs, and I can put it on a RCP dolly with my gold wing or in/on a trailer with the wing and not exceed my GCVWR...
2003 Pace Arrow 36B, W22 Chassis
Ultrapower ECM upgrade, CAI, Wires, Koni FSD