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Old 08-01-2007, 09:28 PM   #1
MatthewHSE
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Does a rear spoiler cut down gas mileage?

I'm thinking of buying a 2001 Buick Regal. The one I'm looking at has a rear spoiler, which is obviously only for looks since it's a front-wheel drive car. Will the spoiler affect gas mileage in any way? It's probably a negligible amount of weight, but I can envision it possibly being quite a lot of drag.

Any insights appreciated!

Thanks,

Matthew
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Old 08-01-2007, 11:37 PM   #2
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Quote:
Originally Posted by MatthewHSE
I'm thinking of buying a 2001 Buick Regal. The one I'm looking at has a rear spoiler, which is obviously only for looks since it's a front-wheel drive car. Will the spoiler affect gas mileage in any way? It's probably a negligible amount of weight, but I can envision it possibly being quite a lot of drag.

Any insights appreciated!

Thanks,

Matthew
If fuel consumption is affected, you probably wouldn't notice it.
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Old 08-01-2007, 11:45 PM   #3
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It creates aerodynamic drag and wind resistance so theoretically, yes, but probably not by too much...depending on how big it is.


Just removed it. Those things are glued on.
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Old 08-02-2007, 12:49 AM   #4
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Unless you're going 150MPH all day, I don't see it creating enough drag to worry about. Asking if a spoiler will decrease MPG for a Regal is like asking if the added weight wearing from a belt buckle will make your dumprtuck slower.
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Old 08-02-2007, 02:24 PM   #5
MatthewHSE
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Quote:
Originally Posted by giant016
Unless you're going 150MPH all day, I don't see it creating enough drag to worry about. Asking if a spoiler will decrease MPG for a Regal is like asking if the added weight wearing from a belt buckle will make your dumprtuck slower.
Okay, I get the point! I just don't understand why you'd add a spoiler to a front wheel drive vehicle anyway, except to look cool, and I figured there'd be a tradeoff somewhere.

Thanks for the help guys!
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Old 08-02-2007, 02:43 PM   #6
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Quote:
Originally Posted by MatthewHSE
The one I'm looking at has a rear spoiler, which is obviously only for looks since it's a front-wheel drive car.


While the others have discussed weight vs mpg, I have to remind people yet again that a rear spoiler is NOT for drag race traction. And a FWD car can use the rear lift reduction of a rear spoiler as much as a RWD car can. And a properly designed rear spoiler can also reduce overall drag by keeping the boundary layer attached to the rear of the car until it gets past the rear.

Due to the way the air boundary layer can come of the body as it goes over the rear window and rear deck, drag is caused and lift is caused from a low pressure zone being created over the rear deck.



Simply saying a FWD car cannot use a rear spoiler is in fact, wrong.

Even a wing that creates downforce can be used on a FWD car effectively, combined with a front airdam that reduces front lift (or creates front downforce). And, the bigger the wing, the lower the speed at which it becomes effective.
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Old 08-02-2007, 02:47 PM   #7
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Why do you think pro race teams put rear wings on FWD race cars?



Do you think it lifts the front wheels off the ground? It's not for drag race traction and it's not for high speeds. It's to increase the speed in the corners by keeping the rear end planted. Why would that matter in a FWD car?

You can increase the average sped around a track with a wing even without adding a single horsepower AND while adding drag that reduces top speed slightly.
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Old 08-02-2007, 07:59 PM   #8
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If you do highway driving, yes, but not by much
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Old 08-02-2007, 09:32 PM   #9
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unless you need rear end stability at medium to high speed ranges to plant your rear end coming out of corners then you might as well take it off, it looks better too

I dont mean any offense to chrisv ethier lol
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Old 08-02-2007, 09:52 PM   #10
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Quote:
Originally Posted by nighthawk
unless you need rear end stability at medium to high speed ranges to plant your rear end coming out of corners then you might as well take it off, it looks better too

I dont mean any offense to chrisv ethier lol

Even at highway speeds it can improve fuel mileage by reducing drag by keeping the boundary layer attached.

Of course, none of us here know whether it will or wont in this particular application. But a blanket "it does nothing but add drag" stands a good chance of being incorrect. Again, just trying to increase the knowledge base of the group...
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Old 08-02-2007, 10:42 PM   #11
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Quote:
Originally Posted by ChrisV
Even at highway speeds it can improve fuel mileage by reducing drag by keeping the boundary layer attached.

Of course, none of us here know whether it will or wont in this particular application. But a blanket "it does nothing but add drag" stands a good chance of being incorrect. Again, just trying to increase the knowledge base of the group...

Question. Since it is impossible to determine exactly whether or not a spoiler will be able to reduce drag by keeping the boundary layer attached, how do cars like the Evo achieve this? Do they specifically engineer their spoiler in such a manner? How would an Evo be affected if the spoiler was removed? I'm just wondering and thank you in advance.
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Old 08-02-2007, 11:01 PM   #12
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Quote:
Originally Posted by Nissan_Altima
Question. Since it is impossible to determine exactly whether or not a spoiler will be able to reduce drag by keeping the boundary layer attached, how do cars like the Evo achieve this? Do they specifically engineer their spoiler in such a manner? How would an Evo be affected if the spoiler was removed? I'm just wondering and thank you in advance.
You big sissy, talk to him like a MAN.

What ChrisV is saying is that it is impossible for us to know about the aerodynamic characteristics of MatthewHSE's spoiler because we don't have the car or the wind tunnel to test it.

Give me a wind tunnel, and I can design aerodynamics for the Evo that'll make it do whatever the f*ck I want it to do...within reason of course.


But I seriously doubt ya boy's wing is increasing gas mileage. I've never heard of wings being able to push a vehicle into a boundary layer to reduce it's drag characteristics...and it sounds quite foolish and physically wrong. Unless the wing is covering a surface that produces higher kinetic friction than the wing itself, I don't see how it can reduce drag. Toying with airflow underneath the car through ground effects is the only way I know of gaining downforce without drag penalty.

Last edited by What : 08-02-2007 at 11:20 PM.
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Old 08-02-2007, 11:28 PM   #13
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Quote:
Originally Posted by Nissan_Altima
Question. Since it is impossible to determine exactly whether or not a spoiler will be able to reduce drag by keeping the boundary layer attached, how do cars like the Evo achieve this? Do they specifically engineer their spoiler in such a manner? How would an Evo be affected if the spoiler was removed? I'm just wondering and thank you in advance.
wind tunnel and a smoke stream

or a CFD design.
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