how come the wings on cars?

It's funny that most people simply give their opinions. There's been a lot of half truths spoken. Most OEM spoilers, with very few exceptions, have no aerodynamic benefit, and are completely aesthetic. Most aftermarket wings you see on cars like civics, the big erector set style wings ARE functional, they just aren't installed for that reason. Most of those type of wings are installed purely for looks and to be "different" compared to everyone else on the road (yet they look just like the guy at the light next to him who wanted to be "different" as well...Ironic, don't ya think?) If properly set up, those wings can be very useful in handling. Some cars, front wheel drive or not, experience a bad lift at higher speeds. My old escort was one of these, and though I never took it on a track, if I had, I would definitely want some sort of wing because the rear of the car started to drift around even going in a straight line, and a properly set up wing would eliminate that, and make for much more sure footed handling.

One thing that car designers want to avoid is to enable oversteer. Understeer is a far more desirable condition.

If at high speed, there's not enough down force on the rear wheels, the rear of the car may swing around, i.e. oversteer. That's why a car designer may put spoilers/wings on the rear of a front drive car.

If it's an ugly contraption obviously bolted on by the owner, it may have no functional use whatsoever.

the sad thing is people do.., really it provides no advantage as it is just pushing down on the back wheels for more drive but in a front wheel drive car that doesn't help. most cars that are produces have the spoilers only for looks and provide no advantage, when you start getting into performance mercs and BMW's is where the spoilers actually start to do something.

its because when your turning a corner at 100 mph you need the back wheels to stick to the floor, and not go sliding towards the outside, which would make you oversteer.

helps the back tires to grip the road around curves and such. But its mostly to make the car look cool.

Aerodynamics.

They think the are in the fast and furius

looks only. (on those cars)