I bought my Thule Atlantis 1200 XT cargo box for a trip from Chicago to Florida and back. I mounted it on the factory cross bars of my 2011 BMW X5. The factory cross bars are very wide compared to the thule crossbars, but the box mounted nicely and was very secure. This box fit 3 airline sized roller boards (suitcases) with room to spare. Two of the suitcases were expanded to full capacity. On the way to Florida, we drove for about 3 hours in heavy rain. Everything inside the box stayed completely dry. Wind noise was barely noticeable even at 80 MPH. Fuel economy was definitley affected by a couple of MPG, but then again, the care was completely loaded and carrying 4 passengers as well. For those of you wondering, my X5 is a diesel and averaged 23 MPG for the entire 3000 mile trip. It normally would get about 25-26 MPG without a load. The box is constructed of thin plastic, so care should be taken when installing/removing/storing. It is light and one person can easily lift and adjust by themselves. The mounting system is incredibly easy to use. I almost bought the cheaper version that you have to mount with a bracket and nuts/bolts, so glad that I did not. Probably the only negative would be that you have to leave the key in the lock any time the box is open. If you keep the key on your car key chain, that may be a problem. I just put it on it's own key chain along with the key for my cross bars and it really did not matter to me. Once on the car, it actually looked pretty good. Another benefit of this box is that it will easily hold 4 or 5 pairs of ski's. I was using a open ski rack which allowed road salt to get all over my skis. Next year the skis will be nice and clean.