I'm a trailering newbie, but I didn't want to own a big-ass truck AND a day-to-day driving vehicle, so I decided to try towing with my 2001 X5 3.0 (90k miles). I too have read all the posts, and found those by 'withidl' most helpful. I'm towing a 20-foot 7000 lb. (with full load) Roadmaster Predator in the Florida panhandle every weekend now for 2 months. I have the Draw-tite weight distribution hitch and an anti-sway system installed (Curt Manufacturing Sway Control). Also installed the Tekonsha Prodigy electric trailer brake controller per instructions found on this forum. I have no problems towing that trailer up and down the mild hills here, but the sway at any speeds over 60 mph is significant. Due to the nature of this trailer (the front half has living quarters, rear half is a garage with the 'true' load), it may have more to do with my weight distribution inside the trailer 'garage', as I may now have less than the recommended 15% of the total trailer weight at the tongue now. I towed this trailer at it's empty weight of 5250 lbs. the entire length of Florida at 70 mph without this problem when I first picked it up.

Beware of the triple-speed blinker issue in your X5 that several of us have experienced. Also, the trailer LED lights will go off about every 10 or so seconds with the vehicle turned off. I can't seem to find a fix for this anywhere on the web, and my dealer is clueless. It does kind of appear that the trailer has an alarm on it at night though....

Overall, I'm happy with the setup as I'm probably never going to be towing more than 300 miles from home, and 60 mph keeps my gas mileage right at 11 mpg anyhow. Any longer distances, and then a little extra speed would be nice, and may require other modifications.

The 3.0 liter engine seems to have plenty of power to move this trailer ably. Some hills have to be climbed in 3rd gear, and per withidl's recommendations, I've been towing in the manual mode on my steptronic transmission to keep engine rpms above 2000 and speed above 55 to keep the torque converter locked up as much as possible.

Good luck, and be safe!

surgeondress