I have used my X5 4.4i to tow my boat. The boat and trailer when fully load is about 5000Lbs. The X5 actually outperformed my F150 in all aspects of towing. Since the X5 cost 2.5X the F150, I use the X5 as a back-up tow vehicle. I would recommend you purchase the 4.4i if you plan to use it for towing.