You've done everything else to the car – it's going quite fast, but it feels uneasy on the road. It's not the suspension, it's not the tyres, it's not the light weight body – but there's something making the car feel like it's riding on a cushion of air. Well, it is, sort of. Welcome to the world where your car is going fast enough (usually over 100kmph) and its aerodynamics are affecting its handling and stability – and also speed. To help you tackle this, there are aerodynamic mods available in the form of spoilers, canards, diffusers and splitters.
Most of these aerodynamic devices are aerofoils, shaped like a weird teardrop (when looked from the side), these use their shape to force the air passing over it to create either an upward or a downward force. In planes, these are are to create lift, in cars they create downforce. These are quite strong forces and thus if your car does not actually go fast enough or has enough power, you may be slowing yourself down by installing aerodynamic aids than making yourself faster.
A front splitter's job is to send the air from the front to other devices around the car, they could include the flat floor, a though-the-hood vent, into the wheel wells or push it outward to the side. Front splitters can also be generating downforce themselves, helping the car tackle high speed corners more effectively by forcing the front tyres down onto the road.
The winglets on the front bumper effectively channel air to the rear, keeping it as clean as possible to help the rear wing or any other device on the body function properly. Winglets which wrap around the the front bumper's corner can even help generate downforce during a turn.
The skirt's job is to prevent the air underneath the car from escaping from the side, forcing it to exit the car from the rear. This in turn helps create a vacuum to suck the car down to the road. Some skirts may have vents directing a bit of the air to the rear wheel wells to cool the brakes down.
The rear diffuser helps accelerate the air coming from underneath the car, which in turn creates a pressure difference underneath, which causes the car to be sucked down onto the road better. A rear wing may not be needed in some cases if this 'ground-effect' is powerful enough.
Finally the rear-wing. One of the most visible form of aerodynamic modifications on a car, their effectiness is limited to how well they are designed. A big wing is useless if the only thing it does is act like a big parachute. You need a wing on your car only if you find that the rear of your car becomes unstable at high speeds, needing the extra downforce to keep it stable. Adding a wing will effect a car's top speed, so be clear about your expectations.
Source : gaadi.com