I understand that side skirts have very little aerodynamic function on street cars that don`t see high speeds. Their sole purpose, racing wise, is to keep as much air from coming under your car and causing unwanted lift. Besides that, I just think on our cars they add a bit of balance to the flow of the bodylines. Plus, I`ve been toying with the idea of actually having my car do a bit of weekend racing at some road courses eventually.