Do cross bars reduce MPG?
- Thread starter Memphisto
- Start date
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I'll bet if you took your cross bars off you could get another 37 feet added to that 14 mpg.......
Could always take off the mirrors.I'll bet if you took your cross bars off you could get another 37 feet added to that 14 mpg.......
A 2024 Limited with the stealth pkg to include the larger engine. Also 4X4, 3:73's, HD tow pkg, factory suspension. Remember these things have the aerodynamics of a brick. It is a friggin' truck!
I could get 20.....if I can find a 10 mile straight stretch of downhill road that I could coast down........
Otherwise 15 if I play nice with the go-fast pedal.....and I don't have cross bars......but I could stick my head out the window and let my ears flap.......
Strangely I get 11 or so when I'm towing our 7000 lb travel trailer at 65 mph....which is better than the 9 mpg I used to get towing with my previous 2021 Ford Ranger......
Otherwise 15 if I play nice with the go-fast pedal.....and I don't have cross bars......but I could stick my head out the window and let my ears flap.......
Strangely I get 11 or so when I'm towing our 7000 lb travel trailer at 65 mph....which is better than the 9 mpg I used to get towing with my previous 2021 Ford Ranger......
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I'm thinking with those ears flapping in the breeze they might cause more wind resistance than cross bars. lol
I admit, I drive "with enthusiasm" and I always use tow mode (with occasional forays into sport mode), use premium, and never never use ASS.
I never worry about mpg....this vehicle is a 5500 lb rolling brick. If I wanted good mpg I would have a.... "SHUDDER"....Prius !!!!
drankinatty
Active Member
I agree the increase in mileage from removing the crossbar would be non-zero, but negligible. You don't provide a picture, but I suspect the crossbar tapers in both the front and rear, has a smooth rounded surface around the perimeter and the upper and lower profiles are roughly symmetric.
There is a reason for that. Much wind-tunnel testing has been done over the years to reduce drag of all protuberances. (things that stick out off the basic body). A well designed rack will follow these basic design considerations.
You can do a rough percentage calculation on how much you would save, and it won't be much. The drag equation is drag = 1/2 * rho * A * v^2, where greek rho is the density of the air, A is the planform area (cross-sectional area) of the cross bar and v being your average velocity (speed).
Now you don't even have to let your eyes roll back in your head saying "oh god, way too complicated" because what you care about is drag of the crossbar divided by the drag on the entire vehicle, so all density and velocity terms cancel and you are just left dividing just the cross sectional area of the crossbar by the total cross sectional area of the vehicle to get the expected percentage of drag contributed by the crossbar.
I haven't done the measuring or the calculation for you, but I would suspect the crossbar contributes somewhere less than 0.1% of the total drag on the vehicle.
So in technical terms, the mileage increase from removing the crossbar isn't going to make a rats-a$$ worth of difference
There is a reason for that. Much wind-tunnel testing has been done over the years to reduce drag of all protuberances. (things that stick out off the basic body). A well designed rack will follow these basic design considerations.
You can do a rough percentage calculation on how much you would save, and it won't be much. The drag equation is drag = 1/2 * rho * A * v^2, where greek rho is the density of the air, A is the planform area (cross-sectional area) of the cross bar and v being your average velocity (speed).
Now you don't even have to let your eyes roll back in your head saying "oh god, way too complicated" because what you care about is drag of the crossbar divided by the drag on the entire vehicle, so all density and velocity terms cancel and you are just left dividing just the cross sectional area of the crossbar by the total cross sectional area of the vehicle to get the expected percentage of drag contributed by the crossbar.
I haven't done the measuring or the calculation for you, but I would suspect the crossbar contributes somewhere less than 0.1% of the total drag on the vehicle.
So in technical terms, the mileage increase from removing the crossbar isn't going to make a rats-a$$ worth of difference
JimmyC
Member
I just did a 850 mile trip running 75-80 in my 2017 Expedition got 19.7 most of the time, if I drive 55-65 I get 21, 18; around town
Glen B Ashcroft
Well-Known Member
i removed cross bars, noisy and car wash issues, the roof never gets clean if you have them on, no mpg difference
ShawnP
Active Member
That tracks. I get about 20 with my 2020 Expedition Ltd., and I get about 14-15 with my 2026 Max Premium stealth, larger engine, 4.4, tow package, etc.
Danm355
Well-Known Member
I have a 2022 Expedition Platinum and I get 23.5 MPG. It all depends on how you drive. If you come off a light or stop sign and really push the pedal you will use more gas. If you wait to the last minute to brake when coming to a light or stop sign you use more gas. I try take my foot off the pedal a little ways back and coast a little if possible. Keeping a steady speed also helps.
Yes. I agree with the Cross Bars being so insignificant of drag in the air, that even at 75 MPH the MPG loss wouldn't amount to a hoot nor be the slightest bit noticeable. However, I would take them off and store them in the garage until really needed, just for a little less wind noise while on the highway, at speed. If it's inconvenient to do that, just leave them on. Lance
You could, in addition to removing the cross bars, run with the mirrors folded in thus reducing the vehicle cross section.I agree the increase in mileage from removing the crossbar would be non-zero, but negligible. You don't provide a picture, but I suspect the crossbar tapers in both the front and rear, has a smooth rounded surface around the perimeter and the upper and lower profiles are roughly symmetric.
There is a reason for that. Much wind-tunnel testing has been done over the years to reduce drag of all protuberances. (things that stick out off the basic body). A well designed rack will follow these basic design considerations.
You can do a rough percentage calculation on how much you would save, and it won't be much. The drag equation is drag = 1/2 * rho * A * v^2, where greek rho is the density of the air, A is the planform area (cross-sectional area) of the cross bar and v being your average velocity (speed).
Now you don't even have to let your eyes roll back in your head saying "oh god, way too complicated" because what you care about is drag of the crossbar divided by the drag on the entire vehicle, so all density and velocity terms cancel and you are just left dividing just the cross sectional area of the crossbar by the total cross sectional area of the vehicle to get the expected percentage of drag contributed by the crossbar.
I haven't done the measuring or the calculation for you, but I would suspect the crossbar contributes somewhere less than 0.1% of the total drag on the vehicle.
So in technical terms, the mileage increase from removing the crossbar isn't going to make a rats-a$$ worth of difference
Also, you could go to "thinner" tires.....from a 65 series to a 70 or 75 series, again reducing the cross section of the vehicle/tires.
Or, you could simply say "Do I really need to concern myself with something so insignificant" ???????
Well, my good ole '011 with the 5.4L Beast engine, 2 cross bars, a bug deflector, side vent covers, Michelin 275/55/20 Defender MS/2 LTX's @36psi averages 15.5-16.8 mpg on the highway@a near constant 65-70mph 5 days/week with 91 fuel.....
And it's 16 years old, with mostly all original parts except for the normal maintenance items...
And although I agree about the brick aerodynamics part, I still find it difficult to believe that a 23 would only get 14mpg under any circumstances, outside of crappy gas, faulty/failing plugs & coil packs, clogged air filters, bad tires and/or suspension parts etc...something bad/unusual has to be going on here....
And it's 16 years old, with mostly all original parts except for the normal maintenance items...
And although I agree about the brick aerodynamics part, I still find it difficult to believe that a 23 would only get 14mpg under any circumstances, outside of crappy gas, faulty/failing plugs & coil packs, clogged air filters, bad tires and/or suspension parts etc...something bad/unusual has to be going on here....
