Roof Rack Fuel Economy

[WTITW]

I took my rack off a couple weeks ago to inspect it and wax the roof. I do that every year but this year decided to leave it off a while to check how the roof rack effects MPG’s.

After a full tank it looks like almost exactly 1MPG with the rack off. I also had a shower privy and large 270 awning but adding those didn’t significantly change MPG’s so I think it’s mostly the turbulence and wind drag load that matters.

Mixed driving 25% city, 75%HWY
Before 14.2
After 15.2

 

[rav8]

I noticed about the same after adding my rack. Doesn't seem to change much either empty or when I have the Thule 614 box up there and loaded. For where it has taken me thus far, I'm happy my GX only guzzles gas.

(Though I think I may have just joined the Valley Plate Leak Club® , I'm probing for a little more validation before tearing it apart.)

 

[jeremy j]

(Though I think I may have just joined the Valley Plate Leak Club® , I'm probing for a little more validation before tearing it apart.)

Sorry to hear that. Seems like it is going to get all of us at some point.

 

[r2m]

I forget, do you have a fairing on yours? If so, when you put your rack back on, maybe do a little test with and without the fairing.

 

[WTITW]

No, just a little wind deflector it came with. Not even sure that's still on. It's not a full fairing. I doubt it would help much, but I'll give it a try if it still exists. I've got the Yakima lock-n-load, which is kind of like a Rhino Rack. Floats above the roof a bit more than Prisnu style.

 

[r2m]

No, just a little wind deflector it came with. Not even sure that's still on. It's not a full fairing. I doubt it would help much, but I'll give it a try if it still exists. I've got the Yakima lock-n-load, which is kind of like a Rhino Rack. Floats above the roof a bit more than Prisnu style.

If you want to make a simple one I have made a template for mine off of one sent to me from Tim and Gamiviti. I can send that to you if you'd like.
It's a 11 x 17 PDF file that you print in three sheets and splice together for the entire fairing. Then trace it onto a sheet of plastic, tin or whatever you'd like to make the fairing out of.
I used clear Acrylic since it's in front of the LED light bar.

 

[re_guderian]

I'm honestly surprised the impact is that small.

 

[WTITW]

Actually went up even more. 1.3MPG, that's nearly 10 percent. Not sure what it weighs but I can lift it onto and off the car myself with some careful effort (I'm a buck fifty) so it seems like its all wind drag.

 

[Cold Iron]

I'm honestly surprised the impact is that small.

I am as well. ~17 years ago I put a Coleman roof rack on my Xterra they were all the rage back then for not a lot of money. I lost 2-3 MPG on the highway it was a solid 3 MPG. But it was not the most streamlined rack out there, just the cheapest at the time. Only kept it on for a couple of months my first trip in the woods the trees wanted it more than the Xterra did. Haven't had one since.

 

[xychromosome]

I just have the aero bars on my stock rails and just the addition of my ski rack holder to carry fishing rods drops my mgs 1-2mps.
Aeordynamics matters!

 

[suitcase]

I get closer to a 2-3mpg loss as well with a roof rack.

 

[WTITW]

I get closer to a 2-3mpg loss as well

my mgs 1-2mps.

What kind of racks do you guys have?

 

[xychromosome]

I just have the stock cross bars. I use these clamps to secure my awning and the ski/snowboard holders clamp directly to the bars. I take those off when not in use.

 

[suitcase]

What kind of racks do you guys have?

My roof rack setup is a set of Yakima round bars, wind fairing, and a Kuat Mini Skinny basket. I usually use a big cargo bag in the basket to carry bulky items like sleeping bags, inflatable paddle board, etc. I don't think I've ever gotten over 16mpg hwy with that set up. In between trips, I've taken off the basket, but the wind noise, even with the fairing, leads me to believe it's not helping the aeroness. Round bars aren't the most aero dynamic shape, but I was hoping the fairing would help more (at least without the basket and cargo bag up top). I had the factory aero cross bars at one point, but I didn't have the confidence to load them up carrying gear. Sometimes I'll have around 150lbs. I think I was doing OK with mpgs when I had the factory aero cross bars. I only have a need for the full rack setup maybe two or three times a year so for the most part I leave everything off.