I bought the Thule fairing, and it has done exactly what it said it would -- it completely took away the annoying whine from my roof-top rack. Not sure if it has added anything in terms of fuel efficiency, but I was mostly looking for blissful silence. The one thing that I would say is that it looks like it will install best if you have the standard square Thule bars. I have a less-common style of Thule bars called "t-slot aero bars". These bars are rounded-H-shaped, and the racks attach in the channels on top. The problem with that type of bar is that the fairing attachments then render that bar useless for then attaching anything else. The fairing attachment simply sticks up too high. I had to get a separate bar for the fairing and leave the two standard bars for my racks. It works fine that way, it was just a hassle and more unexpected cost. If you have questions about what I mean, just look at page 3 of the instructions, and you will get the idea.