Gas mileage with/without rack?

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2017 CX9 GT AWD
Anyone done comparisons of gas mileage when driving with an empty roof rack vs not having the roof rack installed? I rarely use the roof rack and wonder if gas mileage is much better if I just took them off and only used them when needed.
 

Montanaman

Montana/Arizona
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2018.5 CX-9 AWD GT
I'm wondering the same thing . I only use the rack once a year on our long trip and think it looks better with the cross bars off but they are not that easy to remove unless you are a contortionist. I did not get the special tool to get to the screw's. I can't think it would affect it that much of a difference. Maybe 1 mpg. I'll probably just leave then on.
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
Thread bump!!
I'm wondering same thing. My sister has told me it made a big difference on her Sienna.
I've got 2 Yakima fork lifts and never take them off since my CX-9 is garage kept, but would put good money on betting that a rack has an affect on mpg particularly on a long road trip.
 
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Mazda CX-9 Grand Touring 2016
My experience with just the Mazda crossbars in place results in a very small mileage hit. The hit to mileage is much higher with the roof box on the car. The crossbars stay on all winter. The box goes on only for a ski trip with more than 2 passengers aboard.

Anything at all that interferes with the air flow over the body will hurt fuel consumption. The engineers designed the body in the wind tunnel; change the air flow and you upset the maximized design.
 
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'14.5 CX-5 Touring AWD, Soul Red | '14 CX-5 Touring AWD White
I'd be surprised if it was down more than 1MPG. I'd not sweat it really. I have one with the rack and one without one. No difference perceived.
 
I'd be surprised if it was down more than 1MPG. I'd not sweat it really. I have one with the rack and one without one. No difference perceived.

I can believe there is just a minor hit on fuel economy. The only time I've had my crossbars in place, there were also 2 kayaks up there, so no data from me.

But the Noise! Just the crossbars are noticeable starting at 45mph, clearly louder than on my old 328 BMW. Even though they are a pain to remove (and surely also to re-install), I took them off after 2 days. I know others here have posted they hear no noise, but I don't consider myself super-fussy, and it really annoys me.
 
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2021 CX-9 Sig
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2021 CX-5 GT
On a related note, I find that in my 2018 CX-9 Signature, I can get almost 31 MPG on the highway if I follow the stated speed limit (+2). I was a little low on gas and wanted to make it cross the state line and decided to go the speed limit. At times this was 55 (so I went 57) and some times this was 65 (which I went). On my computer, I achieved close to 31 MPG for the ~100 mile trip. Did that the next day again just to see.
 
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cx9
The difference at 55 or 60 is going to be alot less than at 70 or 75. I would just try to drive slower when you know stuff is up there. Rackless, I did (dash indicated) 32mpg on a recent trip by tagging on the back of whatever the slowest car in the slow lane was. Actually one guy was doing like 48, I had to pass them after a while. I couldn't take it. But I was pleasantly surprised that there are still fuel conscious folks out there in the slow lanes. Its the way it should be, that is what the slow lane is for. I did a good portion of the trip @55 behind a huge lowrider on little tiny tires.. :p
 
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Mazda CX-9 Grand Touring 2016
About the noise---There is a front edge and back edge to the crossbars. Each foot has the position marked on it...LF or RR, etc. If they bars are backwards they will make more noise. The rounded edge is the leading edge, and the thin edge is the trailing edge.
 

hnnnnnh123

Member
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Mazda CX 9
I do not notice any additional noises with the OEM cross bars installed. But yes, the kayaks will give you lots of howling noise starting 40mph .