# Car roof rack question (Air diverters) **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [April 24, 2006, 8:17pm UTC](https://boards.straightdope.com/t/car-roof-rack-question-air-diverters/354039 "2006-04-24T20:17:05Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![MacTech](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MacTech](https://boards.straightdope.com/u/MacTech)\ **Post date:** [April 24, 2006, 8:17pm UTC](https://boards.straightdope.com/t/car-roof-rack-question-air-diverters/354039/1 "2006-04-24T20:17:05Z")
I have a Yakima roof rack on my car, set up with a pair of “wheels-on” bike carriers, one’s a clunky old Barrecrafters rig for my old steel Fila Taos singlespeed, the other’s a new Yakima “Claw” style rig… i have noticed a slight drop in fuel mileage due to the increased aerodynamic drag of the rack (2-3 MPG less), i know they make fairings/wind diverters for racks, i’m just wondering if they work or if they’re just a psychosomatic band-aid? in theory, they should work when the rack is empty, _nothing_ will compensate for the drag caused by a bike in the rack though, although the cynical part of me thinks that the aerodynamic change caused by the fairing would be minimal, so, anyone know if these work, or are they just a fancy place to put stickers 😉 ---
**Author:** ![Red\_Stilettos](https://avatars.discourse-cdn.com/v4/letter/r/fbc32d/32.png) [@Red\_Stilettos](https://boards.straightdope.com/u/Red_Stilettos)\ **Post date:** [April 24, 2006, 8:49pm UTC](https://boards.straightdope.com/t/car-roof-rack-question-air-diverters/354039/2 "2006-04-24T20:49:45Z")
I had a Yakima rack on my last car that had attachments for skis. Most of the year, I only had the rack (no attachments) and I could tell a difference in mileage without the fairing. As you’ve noticed, it’s about 2-3 mpg. I never took the fairing off when the ski racks were in place, so I don’t know how much of a difference it made there. The only problem I had with the fairing was that it made my sunroof useless. Absolutely no air came in with the fairing on. However, it was better than the effect of the ski racks. They made the air blow straight down. It was like having a wind tunnel blowing you into the seat. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [April 24, 2006, 9:05pm UTC](https://boards.straightdope.com/t/car-roof-rack-question-air-diverters/354039/3 "2006-04-24T21:05:23Z")
I have a Yakima Load Warrior (with extension). I too, noticed a 3 mpg penalty. I only put it on when I need it.