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Old 06-22-2012, 08:29 AM
 
Location: Lafayette, Louisiana
14,100 posts, read 28,585,552 times
Reputation: 8075

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I remember when the Lancer Evo had those funny bumps on the back roof line to reduce drag. They've done studies of the bumps on whale fins which shows they improve the efficiency of motion for the whales. I've read that the rear spoiler off the roof of some hatchbacks help to reduce drag. With fuel efficiency being a big thing today, has anyone ever seen a vehicle with such devices added and advertised as helping to save fuel by reducing drag as well as showing an actual fuel economy gain? I know the average family sedan or economy compact had spoilers that were for show instead of increasing down force for speed. That's why I picked a car without a spoiler.
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Old 06-22-2012, 08:46 AM
 
Location: Grosse Ile Michigan
30,707 posts, read 79,979,403 times
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No.

If they were not engineered for the shape of your specific car, I cannot see how they could work.

Specially engineered tails can work. They create some sort of air effect behind the car to reduce "suction" for want of the technical term.

Like most things, the cheap add ons are just expensive decorations. A device specially engineered for the shape of your car will not be cheap.
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Old 06-22-2012, 09:08 AM
 
Location: Pikesville, MD
5,228 posts, read 15,325,054 times
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lol
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Old 06-22-2012, 09:13 AM
 
Location: Lafayette, Louisiana
14,100 posts, read 28,585,552 times
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Quote:
Originally Posted by Coldjensens View Post
No.

If they were not engineered for the shape of your specific car, I cannot see how they could work.

Specially engineered tails can work. They create some sort of air effect behind the car to reduce "suction" for want of the technical term.

Like most things, the cheap add ons are just expensive decorations. A device specially engineered for the shape of your car will not be cheap.
What about factory spoilers designed from the factory with the purpose of reducing drag?
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Old 06-22-2012, 11:23 AM
 
Location: SF Bay Area
5,994 posts, read 20,158,010 times
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Most factory spoilers don't do a whole lot although the more performance oriented cars do have spoilers that reduce lift (by adding drag). My Genesis Coupe doesn't have a spoiler and I don't think I'll ever want one. Aero parts on cars are more of a cumulative effort. Cars that are designed for reduced drag typically have headlights shaped to direct air around the mirrors, side mirrors designed to reduce drag, rear taillights with protrusions that direct air around the rear of the car along with the actual shape of the body, flat underbody, fenders, hood, trunk, etc. I don't think adding any one thing will significantly improve mileage particularly on cars that aren't obsessively designed to reduce drag from the factory.
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Old 06-22-2012, 12:43 PM
 
Location: SF Bay Area
13,520 posts, read 22,180,387 times
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FWIW, this series of articles say these air vortex generators work: http://autospeed.com/cms/title_Blowi...1/article.html
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Old 06-22-2012, 02:18 PM
 
Location: Chicago
38,707 posts, read 103,366,361 times
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Quote:
Originally Posted by sailordave View Post
I remember when the Lancer Evo had those funny bumps on the back roof line to reduce drag.
That's not their function. Their function is to generate air vortices to improve the function of the rear wing to generate more downforce and thus reduce rear lift at speed. The Evo is one of the few production cars whose rear wing is actually functional (albeit at substantially extralegal speeds) and not merely cosmetic. I don't know that the roof-mounted vortex generator meaningfully adds to the wing's functionality -- probably more gimmicky than anything.
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Old 06-22-2012, 03:57 PM
 
6,351 posts, read 21,559,177 times
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Sorta relevant to the topic; I'm sure you all have seen the fairings that have begun to sprout from the bottoms of and even the rear doors of big truck trailers. The EPA has a new "Smartway" program that certifies such modifications in the belief that they greatly enhance aerodynamics and thus save fuel. Well, for those of us that actually drive these things up & down the road, many of us think they're a real hassle. The fairings that hang along the bottom of the trailer make inspecting items like air lines even harder. And out here in the "real world" of high curbs, railroad tracks and other objects waiting to tear these aerodynamic devices clean off (or at least damage them) we wonder whether the fuel savings is REALLY more than the cost of purchasing, installing and maintaining them... And, by the way, suppose your trucks run up and down the I-5 corridor in CA, OR & WA; how much fuel are you like ly to save when the wind is always blowing against the SIDES of your trailer?
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Old 06-23-2012, 04:04 AM
 
Location: WI
3,961 posts, read 11,044,597 times
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i'd think the wings/spoilers that had some "boy racer" looks but also maintained function were the active ones mostly used by Porsche (or like on the older VW corrado) or the first gen Mitsu 3000gt vr-4 that had active front and rear spoilers. The rear ones creating downforce and the vr-4 drawing the car closer to the pavement. But in those cases it was performance based; i doubt anyone driving one of those models spent much time watching the gas gauge lol.
I dont see how bolting something on a car after the fact can do much good. Though per the post on semis i have seen a few on the road and i thought the same thing--"ok i can see trying to cut thru the air better but how do you get at things when you need to"... so glad to see a user post on that one (i'd still assume those on the top of the cab do help deflect air over the trailer, in turn giving some mileage benefit?)
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