Does anyone know what effect the rear spoiler on the xb has on gas mileage?

Hurt it? make it better?

Thanks

 

I'm not sure if it will affect it too much if at all. Probably it would get better mileage without it, but not enough to notice. I could be wrong, though. I guess next time I'm in Charlotte, NC. I'll stop by DEI and have them throw it in the wind tunnel..LOL

 

I think it might help MPG's it if they designed it correctly and not for looks, but I wanted to be sure

I was wondering if anyone had done tests or a windtunnel on it.

Thanks though

 

also if it helps with stability at higher speeds on the highway...

 

As far as stability...HAHAHA. Mine is so flimsy, it'll probably fly off before I got to a speed where it would actually do any good!
If anything, it will probably rob MPG, But it will be in tenths or even hundredths. It will not be noticable unless under a totally controlled environment such as a wind tunnel and even then it will be very very small.

 

It is purely eye candy...no practical function.

 

Like most of the aftermarket add-on wings ad spoilers you see on cars these days it is there to add to the visual element of the car. Done right a spoiler is not necessarily a wing - note the almost verticle spoiler you see on NASCAR bodies designed for 200+ miles per hour. Other shapes may be flat and sit low due to the shape of the car. The "Whale tail" spoiler on the late 70's and eraly 80's Porsches is an example. You may notice that the factory desiged and attached spoilers seen on a lot of the cars are generally not very wide thus minimizing the actual effect that one would provide.

Most of the wings your will see out there are not "tuned" to the shape and aerodynamics of the car that they are attached to. Actually, they may completely destroy the aerodynamic envelope doing more harm than good. The only way you can ensure that the spoiler you are putting on the vehicle is actually doing some good is to put the car into a wind tunnel and blow smoke trails over the shape of the car to see where the envelope sits then apply the spoiler to the car in such a way as to compliment the envelope while adding downforce the rearend. Which brings up another point. A spoiler pressing down on the rearend of a front wheel drive car seems, to me, to be somewhat counterproductive. If anything I would think that you would want something more along the lines of a canard style wing on the front of the car holding and stabilizing the front end and a low drag tapering rear end to minimize turbulance.

 

I believe it’s purpose is to divert airflow into the vacuum that is formed by the square
shape of the back of our box at highway speeds. That dead space causes an increase
in drag and therefore a reduction in MPG. It is not intended to provide any down force
and I think that it helps our milage a lot. It also looks nice on ther car.

I'm not an Aerospace engineer but I play one in my basement.

 

Not al wings are made for downforce. A friend with a WRX told me his wing helped with stability at higher speeds. Of course, he was driving very fast to notice it.

I was watching 'drifting' last night and noticed that all the cars had wings?!? I don't see how this would help unless it was tuned or turned UP to actually lift the rear a bit. I was puzzled. Anyone know about this? Is it just a marketing stunt?

 

I have not noticed any change in my milage from my CF spoiler. So I think it really just adds a little weight & looks, thats about it. So far my gas milage range is 31-39mpg depending on what time of day + how I drive. I have a good deal of mods that most ppl say hurt your milage, so if thats true I could have been getting over 40mpg with out my SRI, Exhaust & 17" wheels

 

I'm with you. I would doubt that it would really effect the MPG, for or against, by any noticable difference.

Want better MPG? Keep teh speedo around 55mph.

 

Moved to DC...

 

Actually for the Xb I think the most appropriate "wing" would be something that has struts coming straight back from the top of the box going back about a foot or so. Then instead of a flat wing simply use a round pipe. This would avoid any adverse effect from the airflow and enhance the shopping cart appearance.

 

the wings are cosmetic at best. I installed mine in the hopes of drafting a little air over the rear window to decrease the dust build up.

 

Most of the dust comes from air from the bottom and the basic shape of the car causes it. Thats why all wagons (most anyway) and SUVs have the wipers...it's just the shape...wing or not, you're going to get it.

 

we knows where the dust comes from, and we knows it will happen, that's why i'm "hoping" some air being forced down from the top will keep it down a bit. The shape of the stock scion wing has a curved, open inside.

Course I could always take a sheet of bounce "anti-static" fabric softener and rub it all over the back, so the dust won't stick, plus it will smell great


singleshot

 

From some early discussions about MPG, the factory spoiler seems to be there to help break the vacuum (reduce the drag for those in public skool ) on an xB enough to get some of the better gas mileage readings.

 

I 2nd It is purely eye candy...no practical function.

 

A spoiler 's function is to put a downward force on the rear end using the air stream passing over the vehicle.
It's use on production cars came to life with the light rear ends of front wheel drive cars.
Below 40 there is a drag that causes some amount of mpg loss. Vey little, but enough that manufactures consider it.

VW and Porsche implemented a speed activated rear spoiler in the 80's. VW put in on the Corado in 1989. It was flush to the body and raised up at about 40mph. Porsche did it for a third reason on the 911 for more "forced" air into the intake for the air cooled engine.
They did this because of the air drag at low speeds, mpg loss, and to get the spoiler/air intake in the air stream at high speeds for better rear traction.

It does work. If you don't think it does, put your head out a sunroof going over 40 with a hat on. Or sit passenger and play hand air plane out the window.
How well it works on a certin car. Like the box. IMO, I would almost say its more eye candy than function. Other wise it would be standard equipment. The mpg loss, even very little, over handling was not worth it to Toyota.

 

Rear spoilers do nothing for FWD cars....