Roof rack and mileage?

[Hakkapeliitta]

How much does roof rack affect on mileage? I´m wondering about this because the Saab I´m driving at the moment (will get the OB on thursday...yeeehoow) and if I have anything on the roof, like bike, roof box etc. the effect is significant. Just a roof box alone makes almost two liter / 100km difference ~ mileage drops from 29 to 23,5mpg on a highway driving. I´m wondering if the OB is any different on this? And I´m talking about 2.5i CVT.

[rasterman]

I can't speak for the new CVT models, but I've seen similar consumption increases on my Outbacks with roof loads. The consumption increase is extremely variable with speed- you'll burn a lot more fuel over 62mph-100km/h. If you keep the speeds significantly under that, you won't notice much of a hit.

[reddoak]

Yes, it is significant. On mine, just putting the roof basket on drops it by 3-4 mpg.

On my friend's 2012 Impreza, with the 2.0 and CVT, installing the crossbars drops it by 2-3 mpg.

[tirolerpeter]

I have experienced significant gas milage drops using roof racks and cargo box (Thuli ski box) in all my vehicles. Since I only rarely need the extra capacity I even remove the cross bars on my 2.5i unless needed. Remounting them only takes minutes so I prefer to run without the added drag.

[Hakkapeliitta]

So this sounds pretty much normal to me. Same as other cars. I was just curious if CVT has any positive or negative effect on that. And I never use cross bars if not needed. Only for trips where some extra stuff is needed.

[rasterman]

The CVT will give you better overall mileage than the other transmissions, but it can't bend the laws of physics when you're trying to drag a weird shape through the wind at high speed.

The CVT really only puts the outback on par with 2WD efficiency while maintaining the benefits of AWD.

[sbpark]

I also noticed about a 3-4mpg loss with just the empty cargo basket on the roof, and even with just the crossbars and a pair of surfboard pads on the rails and no board on top you lose 1-2mpg. As much as I hate some aspects of the design of the roof racks on the 2010-2012, I can say that I appreciate that when you aren't carrying anything on the roof you can fold them away. It definitely makes a difference for the days I work, since I commute 70 miles round trip, which is three days a week. I surf 3-4 days a week, and it's just an extra couple of minutes, if that, to fold out the racks, put on the pads and load my board. well worth the extra 2 minutes in order to save a measurable difference in mpg.

[gaewsky1]

On my 2.5 CVT my mileage dropped about 5-6 mpg. I was getting about 27-28 mpg on highway and with the basket it dropped to about 21-22 mpg. After the trip I immediately took it off. It was empty at the time.

[Fiala06]

Originally Posted by gaewsky1

On my 2.5 CVT my mileage dropped about 5-6 mpg. I was getting about 27-28 mpg on highway and with the basket it dropped to about 21-22 mpg. After the trip I immediately took it off. It was empty at the time.

That's pretty much what i got on mine except I had bike racks up there.

[tirolerpeter]

I live in UT where many people (including me when necessry) use roof racks for sports equipment. What amazes me is how many people leave those "guillotine" type of ski racks mounted on their vehicles year round. They create an amazing amount of turbulance and drag. They have to be creating a 3-5 mpg fuel penalty for no reason. With all the concerns over fuel milage, why would anyone do that?