# Small overhang on back top of larger vehicles? **URL:** \ **Category:** Factual Questions\ **Created:** [June 28, 2011, 1:02pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131 "2011-06-28T13:02:25Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [June 28, 2011, 1:02pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/1 "2011-06-28T13:02:25Z")
What is the deal with the new small overhangs that they are putting on boxier vehicle’s top backend? It looks terrible, but I am guessing it somehow shapes airflow and therefor helps fuel efficiency? It is way to ugly to be stylistic. I first noticed it on Toyotas, so I call it the “Toyota Tail.” I have noticed it on some other vehicles also. [4Runner](http://images.thetruthaboutcars.com/2010/04/2010-toyota-4runner-limited-_4_.jpg) [Matrix](http://www.cardata.com/images/2009/Toyota/2009_toyota_matrix_wgn_2.jpg) [Rav4](http://images02.olx.com/ui/1/92/17/15648517_1.jpg) [Land Cruiser](http://www.roadfly.com/new-cars/wp-content/uploads/gallery/2008-toyota-land-cruiser/toyota-land-cruiser.jpg) [Sienna](http://www.caranddriver.com/var/ezflow_site/storage/images/reviews/car/10q1/2011_toyota_sienna-second_drive/gallery/2011_toyota_sienna_le_awd_photo_26/3274274-1-eng-US/2011_toyota_sienna_le_awd_5_cd_gallery.jpg) ---
**Author:** ![Sparky812](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@Sparky812](https://boards.straightdope.com/u/Sparky812)\ **Post date:** [June 28, 2011, 1:05pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/2 "2011-06-28T13:05:51Z")
They’re not new, basically they are what’s called a [spoiler](http://en.wikipedia.org/wiki/Spoiler_(automotive)) ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [June 28, 2011, 1:21pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/3 "2011-06-28T13:21:32Z")
> [@Sparky812](#): > > They’re not new, basically they are what’s called a [spoiler](http://en.wikipedia.org/wiki/Spoiler_(automotive)) Please fight my ignorance on this, but aren’t spoilers mostly useful at high speed by keeping the back wheels on the gound? That doesn’t seem so applicable for front wheel drive vehicles and non-sports cars. That leaves an aesthetic portion. Maybe some people think it looks good? ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [June 28, 2011, 1:27pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/4 "2011-06-28T13:27:19Z")
> [@Hermitian](#): > > Please fight my ignorance on this, but aren’t spoilers mostly useful at high speed by keeping the back wheels on the gound? That doesn’t seem so applicable for front wheel drive vehicles and non-sports cars. Read the article first. Carefully. Then again for comprehension. ---
**Author:** ![Captain\_Morgan](https://avatars.discourse-cdn.com/v4/letter/c/bc8723/32.png) [@Captain\_Morgan](https://boards.straightdope.com/u/Captain_Morgan)\ **Post date:** [June 28, 2011, 1:27pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/5 "2011-06-28T13:27:26Z")
Did you read the article? “Spoilers for cars are often incorrectly confused with, or the term used interchangeably with, wings. Automotive wings are devices whose intended design is to generate downforce as air passes around them, not simply disrupt existing airflow patterns.” ---
**Author:** ![anson2995](https://avatars.discourse-cdn.com/v4/letter/a/c77e96/32.png) [@anson2995](https://boards.straightdope.com/u/anson2995)\ **Post date:** [June 28, 2011, 1:30pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/6 "2011-06-28T13:30:40Z")
> [@Hermitian](#): > > Please fight my ignorance on this, but aren’t spoilers mostly useful at high speed by keeping the back wheels on the gound? That doesn’t seem so applicable for front wheel drive vehicles and non-sports cars. It reduces air turbulence, which is supposed to increase gas mileage. ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [June 28, 2011, 1:49pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/7 "2011-06-28T13:49:12Z")
Sorry about that, I confused spoilers and wings. Ignorance fought. But the wiki article also mentions that “Often spoilers are added solely for appearance with no thought towards practical purpose.” This is what I am really trying to get at. Are these things showing up on cars because they are actually good for something or is it just another fad? Spoilers have been around for a long time and I have never seen them on large slow SUVs before, so they can’t be that useful. ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [June 28, 2011, 1:59pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/8 "2011-06-28T13:59:40Z")
My impression, and it may be totally wrong but it seemed like a practical application, was that the ones you see on SUVs are designed so as to reduce the amount of dust that collects on the large rear window of your typical vehicle. This would be increasingly important if you have that window open as you’re driving, especially off-road. Maybe it also helps to reduce the amount of water rivuleting across the surface and distorting the view during a rainstorm. ---
**Author:** ![jayjay](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jayjay/32/6765_2.png) [@jayjay](https://boards.straightdope.com/u/jayjay)\ **Post date:** [June 28, 2011, 2:52pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/9 "2011-06-28T14:52:02Z")
The [Malibu Maxx](http://www.netcarshow.com/chevrolet/2006-malibu_maxx_ss/800x600/wallpaper_04.htm) has one, too. ---
**Author:** ![RaftPeople](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@RaftPeople](https://boards.straightdope.com/u/RaftPeople)\ **Post date:** [June 28, 2011, 2:58pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/10 "2011-06-28T14:58:40Z")
> [@](#): > > What is the deal with the new small overhangs that they are putting on boxier vehicle’s top backend? It looks terrible, but I am guessing it somehow shapes airflow and therefor helps fuel efficiency? It is way to ugly to be stylistic. Are you certain you are in the majority and not the minority on this point? Seems a little presumptuous to think that what you like is what most people like. > [@Hermitian](#): > > This is what I am really trying to get at. Are these things showing up on cars because they are actually good for something or is it just another fad? Spoilers have been around for a long time and I have never seen them on large slow SUVs before, so they can’t be that useful. Regarding the gas mileage reason: When an SUV goes 60, is it going slower than other cars going 60? ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [June 28, 2011, 3:09pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/11 "2011-06-28T15:09:33Z")
I’m fairly sure the “keeping crap off the back” is the main reason why they’re on SUV’s and other boxy cars. On snowy roads, the dirty water kicked up off the road rapidly gets sucked into the vortex behind a flat-backed car, soon rendering the back of the car completely opaque. The spoilers actually do make a big difference in breaking up that back vortex and keeping crap off the back of the car. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [June 28, 2011, 3:27pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/12 "2011-06-28T15:27:52Z")
I don’t think it’s for looks, no one looks there on a SUV anyway. If it weren’t there, you’d basically have a square and a lot of turbulent air swirling around the window. Adding a spoiler certainly smooths that out. It may help keep the window clean but I’ve never noticed. In my experience, the area under the spoiler is usually pretty gunky and water runs off of it onto the window, leaving streaks and depositing even more gunk. Of course, vehicles and spoiler designs vary. ---
**Author:** ![Sparky812](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@Sparky812](https://boards.straightdope.com/u/Sparky812)\ **Post date:** [June 28, 2011, 3:42pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/13 "2011-06-28T15:42:54Z")
Simply put (from the wiki article): > [@](#): > > A **spoiler** is an automotive aerodynamic device whose intended design function is to ‘spoil’ **unfavorable air movement** across a body of a vehicle in motion. …bolding mine. Dirt, rain, snow, etc. accumulating on the rear window may all be caused by these unfavourable air movements. Other factors may be wind noise, rear wiper problems, or even exhaust direction. ---
**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\ **Post date:** [June 28, 2011, 4:12pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/14 "2011-06-28T16:12:30Z")
> [@GreasyJack](#): > > I’m fairly sure the “keeping crap off the back” is the main reason why they’re on SUV’s and other boxy cars. On snowy roads, the dirty water kicked up off the road rapidly gets sucked into the vortex behind a flat-backed car, soon rendering the back of the car completely opaque. The spoilers actually do make a big difference in breaking up that back vortex and keeping crap off the back of the car. I’m with this explanation. When we got our first minivan (in the 80s, when they were first hitting the market), the back window would get completely occluded with dust in just a few days. My father installed a rather ugly aftermarket spoiler or wing or whatever you want to call it over the window, and it cut down on the dust dramatically. ---
**Author:** ![svd678](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@svd678](https://boards.straightdope.com/u/svd678)\ **Post date:** [June 28, 2011, 5:24pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/15 "2011-06-28T17:24:56Z")
My father told about a panel truck he bought, with no back door. No one would ride with him and he had headaches until he got rid of it. ('30s) No spoiler! They thought there was something wrong with carburetor or something. ---
**Author:** ![yanceylebeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yanceylebeef/32/12290_2.png) [@yanceylebeef](https://boards.straightdope.com/u/yanceylebeef)\ **Post date:** [June 28, 2011, 5:59pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/16 "2011-06-28T17:59:47Z")
I can’t believe no one has used spoiler tags yet. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [June 28, 2011, 10:01pm UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/17 "2011-06-28T22:01:46Z")
Roofline spoilers are nothing new on big vehicles. My family used to have a 1973 AMC Ambassador station wagon, and this monster had a spoiler (covered with wood-grain vinyl!) at the top of the back window. Much like **svd678** ’s father’s truck with no back door, it was common to drive station wagons with the back glass down, so anything to shape airflow and keep the engine’s exhaust from coming in to gas the kids in the rear-facing seat is probably beneficial. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [June 29, 2011, 1:07am UTC](https://boards.straightdope.com/t/small-overhang-on-back-top-of-larger-vehicles/587131/18 "2011-06-29T01:07:14Z")
Wow. Is the the SDMB? Lacking the spoiler in question, airflow over the top of the vehicle will swirl back when the roofline ends and swirl against the rear window (back of vehicle). This turbulence is friction and maybe even have a slight sucking effect. If you extend the roofline via a spoiler the air will swirl down but a pressure bubble, for lack of better words, prevents the turbulence from buffeting against the rear window (back of vehicle). In NASCAR, you see this effect when someone rides up to the rear of the bumper in front of them. Without the cars touching, the lead vehicle gets an aerodynamic boost, because the airflow that would drag against the rear of the lead car is diverted over the car that is right up behind the lead vehicle. That spoiler trailing off the back of SUVs/Vans is to reduce drag and lend one more little bit of help towards fuel economy. .