roof racks =crappy gas mileage?

and those stupid boxes that people love make it even worse.

box that people love? do you mean the XB or those carrier boxes.?

Yep, that's about right.

My 96 GTi, 2.slow got 31 mpg nekked (with my big 215 pound behind in the left seat and junk in the trunk). With empty roof racks, 28 mpg. With two bikes 23-24 mpg.

With hitch rack, no mileage hit.

Over the roof is where the air stream is compressed after the hood and windscreen direct it upwards, so the denser air creates even more drag.

Heh.... nice thing about those boxes is they come off. Too bad folks are either too lazy to take them off when they aren't using them, or they think that burning 15% more gas is worth looking cool.

its definitely true. my corolla gets just about 30+ mpg with the roof rack on, and it would normally get 35+ (even tho the sticker said 40 mpg when i bought it, i don't think i have ever gotten 40 mpg with it).

I put mine up for sale locally. I go riding every weekend for exercise so I do keep it on so I dont have to worry about scratching the car taking it on and off. Im gonna go order a trailer hitch for my XB and pick up a used hitch rack and end this wallet killer.

Yep. My Fit takes a few mpg hit with bikes on the roof. Not so much with the bare rack, though. I need the roof rack to carry a canoe around (longer than the car), but I'm working out a way to get a hitch rack to carry bikes. I'll be selling my Thule Sidearm carriers to help fund the purchase. I need a hitch rack for my Fit, also, but it'll be nice to be able to use the hitch rack on the wife's Jeep Liberty, also. I currently carry bikes inside the Fit on a DIY fork mount.

I really want a Kuat rack, but I'd probably be happy with any solid tray-style hitch rack.

I have a Camry too with a tray-style Thule hitch rack. Very minimal impact on mileage compared to what I've heard about roof racks. Only problem with a hitch rack is your rig taking a lot of road salt slush-n-spray driving around snowbelt states.

yeah I have an SE camry and all the hitches I see dont fit because of the ground effects.

I think mine drops from 48 to 44ish with a bike on there....

TDI

Putting a fairing on the roof rack will almost eliminate any lessening of fuel economy.

And don't rag on roof boxes... I actually get better MPG with my box on my roof. Mind you, I have an '01 Forester which has a worse coefficient of drag than a cement truck, but nonetheless the cargo box does indeed smooth the air out in some magical way.

PS I am not one of those people who drive around with a cargo box on all the time

XJaredX said:

Putting a fairing on the roof rack will almost eliminate any lessening of fuel economy.

And don't rag on roof boxes... I actually get better MPG with my box on my roof. Mind you, I have an '01 Forester which has a worse coefficient of drag than a cement truck, but nonetheless the cargo box does indeed smooth the air out in some magical way.

PS I am not one of those people who drive around with a cargo box on all the time

Click to expand...

There is logic to your reasoning. I calculated my fuel economy once with a 16ft canoe on my Fit driving across the Appalachians, and I AVERAGED 35mpg. With a boat bigger than my car on the roof.

Only time I've come close to that with bikes was when I had a stiff tailwind on a straight highway.

I have a fairing on my car, still sucked

XJaredX said:

Putting a fairing on the roof rack will almost eliminate any lessening of fuel economy.

Click to expand...

That's way too general of a statement to make any sense. There's still going to be a hit, depending on the car, depending on the rack, depending on the exact location of the rack, and so on. Putting the bikes up there will still cause a rather dramatic loss in milege, not to mention that a fairing may simply delay the speed at which the airflow starts to seperate excessively from the upper surface (but it may also cause that seperation, again depending on the auto).

yup, w/my GOLF TDI i see about 5-15% drop in MPG's,
and for my GOLF TDI, going from 40-50 MPG down to 35-42 hurts quite a bit.

I have an 07 Camry SE. Try playing around with the rack placement on the car. Technically you shouldn't but I haven't had any problems with it so far.

The key is to place the fairing on the same plane as the windshield. Yakima's specs puts the front at the bend in the A pillar of the side window probably for stability. I just mounted it a few inches closer to the windshield and so far has only reduced MPG by 1MPG or almost none.

Try at your own risk. hahaha

It still....

XJaredX said:

Putting a fairing on the roof rack will almost eliminate any lessening of fuel economy.

And don't rag on roof boxes... I actually get better MPG with my box on my roof. Mind you, I have an '01 Forester which has a worse coefficient of drag than a cement truck, but nonetheless the cargo box does indeed smooth the air out in some magical way.

PS I am not one of those people who drive around with a cargo box on all the time

Click to expand...

.... increases frontal surface area... the biggest factor in aerodynamic drag. Heh.... they say you can gain another 3% gas mileage at freeway speed by lowering your car an inch.

I highly doubt you get better mileage with a roof box (again, the surface area thing, not to mention wake drag), but if that is what you are seeing....

On my 2000 Nissan Maxima, I would usually average 25-26 mpg in mixed suburban/highway use. When I added Thule feet and square bars, plus a Yakima King Cobra and a Yakima Raptor, my average would usually be closer to 24mpg. I didn't have a ton of mileage with bikes up top, but I think the mileage wasn't much worse. The hit was small enough for me to find it worthwhile. I previously had a trunk rack that I had bad experiences with, and wouldn't go back to one. I would use a hitch rack in the future, but for now I'm happy.

It really depends on the vehicle. My '89 Honda Civic wagon RT4WD gets 27-28 with no rack, 27 with rack but no bikes, and 26 with bikes.

My wife's '06 Jetta 2.5 gets 31 with no rack, and 25 with bikes...

MPG on my wife's Rabbit didn't change with the addition of a roof rack with two carriers.