I'm seeing a high rate of mpg loss after installing my bajarack. I'm getting even with the mpg I had with my lifted metal heavy (metal bumper, etc.) Fj.
I'm in the 14's and 15's and I haven't even installed the lift yet. But, I am still in the break in period so I'm hoping I gain a little back.
The MPG loss with my roof rack with normal driving wasn't even noticeable (Baja short rack)
I specifically got a short rack for that very reason actually. The airstream over the top of the cab is not affected much by the rack and light as the leading edge sits back in the vacuum layer for the most part.
I have an ARB touring rack - it's 3/4 length of the roof
I second what warthog said about the rack sitting back.
My mpg was 18.2-18.4 prior to the rack and now I'm getting 17.9 - 18.1
Minimal loss in mpg compared to other reports out there
I saw no difference with my rack (unloaded of course). As soon as I put anything up there the mileage drops... But if I'm putting stuff on top that means it's full inside so it's weight along with wind resistance at that point.
I had Yakima Control Towers on my last 4runner. They were fantastic for easy on/off of the roof rack. I custom made a basket that fit with the yakima bars and it worked great to toss on when I needed it and leave it at home the other 95% of the time. If you want the best mileage, that's probably the best way to go.
You could build something similar for whatever mounting style you decide to use if you get rid of the factory rails. There are a lot of different quick release options out there that could be welded on to most roof rack feet.
At 214k+miles on my 2006 4Runner and never having used the roof rack, I decided to remove just the cross bars. After 2 weeks and a couple of trips in excess of 50 miles, I have gained 0.2 MPG per the "computer". Even with my mixed driving- local and some longer distance, it is holding at the new 18.5 MPG. Oh happy day.