Q: http://blog.wired.com/cars/images/2008/08/28/viper_acr_01_3.jpg i would like to know how spoilers (like that link above) affects the car not only by the looks, but does it help performance at all? maybe it helps cut back the wind resistance or something? Oh I see. So in that case spoilers do very little to benefit FWD cars then correct? also how do you know your spoiler is too much weight for your car to start decreasing your car's performance? what equation must you take or how powerful must the car be?
A: Depends on the spoiler. From what I've heard some factory style spoilers do help aerodynamics while some of them are purely for show and create additional aerodynamic drag. However a big one like in that picture is more or less for creating downforce at high speeds. A car needs traction, low weight and a lot of power to get up to speed. Weight would add traction but slow it down and create additional inertia which is always bad when you are trying to get moving or stop. So to prevent cars from getting lift at high speeds (a good thing for airplanes, not a good thing for wheel driven vehicles) aerodynamics play a big role and you can see on some cars there is a bit of a spoiler on the bottom of the front bumper and in extreme modified cases a huge one on the top of the trunk. However you do have to take in consideration when buying a spoiler for a car what it's going to do, if you get too much rear downforce and not enough up front you are going to have less traction on the front end which can lower grip in high speed turns and in front wheel drive vehicles can also cause the tires to slip instead of spin meaning less power to the ground and more wear to the tires.