What are 'spoilers' for on a car?

Question

My previous question had the wrong term; I mean the bar on the back of a car, right above the trunk; isnt' that a 'spoiler' what the heck is it for? Thanks for the previous answers, but I messed up!!

Answer 1

They break up the air flow in the back of the car, to keep a vacuum from forming, which drags on the car, making it slower/ possibly less efficient. Some can also produce down force, using the wind to force the car down harder on the ground. This give extra grip, and helps maintain control. (In this case, it also slows the car down a bit, because forward motion is converted into downward force.)

On most cars, they're purely cosmetic, they don't really do anything. I'm sure they have some sort of effect, but mainly they're there because they look "sporty." I call these "trunk handles."

On some cars, they are in fact designed to do what they look like they do. Examples would be the Subaru Impreza WRX STI and the Mitsubishi Lancer Evolution. Those cars have functional spoilers.

Some aftermarket spoilers also actually work. But most that you see are probably just there because the owner thought it looked cool, and even if they ARE functional, they probably aren't capable of noticing.

Ones that are actually designed to do something other than look cool generally don't do much at less than highway speeds, because forces associated with air flow increase exponentially with speed. Since racing generally takes place at higher speeds, spoilers are more significant there. (However, it can reduce top speed.)

Answer 2

A spoiler is essentially a wing on the back of the car. It's function in racing is to push the back end of the car down to allow it to maintain traction at higher speeds. They usually work in unison with many other aero-dynamic features such as venturi tunnels, front splitters or chin spoilers, canards, etc. Formula one cars are perhaps the best example of this sort of usage as they take full advantage of every aerodynamic feature they can.

With that said:
On most production street cars they are purely decorative. You will never go fast enough with a street car that you would need this sort of thing. It's only when you are hitting tripple digit speeds that this sort of principle comes into play. At normal highway speeds you simply aren't going fast enough to generate downforce, nor would you need it as highways do not have sharp corners like you find on a racetrack. In fact it may actually create more drag decreasing your fuel milage.
Yes there are some high end sports cars which have real functional spoilers but they are really few and far between and typically cost 6 figures. The spoilers you see on Honda accords and Chevy malibu's for instance are not functional.

Answer 3

On a street car they serve no purpose whatsoever, purely cosmetic. On a high performance race car, a spoiler is designed mostly to keep a certain downward pressure on the rear of the car, reducing spinout probability and other negative effects. The wings you see on drag racers are spoilers too and they are almost infinitely adjustable to do different things for the car.

Answer 4

Mainly for looks. In High performance cars it actually directs airflow to reduce drag and increase handling (by forcing the car lower to the road at high speeds. But in most cars the speeds they travel they get very little if any benefit from them.

Answer 5

what you describe on the rear of the car on the trunk is a "spoiler".... they cut down wind turbulence and allow for greater stability due to the fact the air passing over them helps to hold the rear of the car down providing for better traction...and YES they DO perform a function on STREET cars!

Answer 6

it helps the car fly throw the air going 500hp it helps trust me