NitroZ

Reality is from an aerodynamic view point, yes they do work in many ways. However, only after about 75MPH do you get any gain. And for max gain, you need to have a rear diffuse panel installed as well. Air coming from the topside of the car swirls clockwise at the back of the car, air coming from underneath swirls counter clockwise in the same area. This creates disruptive turbulence. You want the air to pass over the car and under the car as smoothly and quickly as possible. This is what these two items do. In conjunction, down force is created. Which is always what you want for top speed and handling.