a system of fairings to streamline the underside of a vehicle , including airfoil - shaped fairings to streamline elements of the vehicle &# 39 ; s axle / suspension system . such fairings may be pivotable and linked to the frame or body of the vehicle in such a way that they adaptively provide down - force or lift , respectively countering the tendency for a wheel to rise off the surface of the road or be squashed against the road due to cross winds or sharp turns . fairings so configured not only increase efficiency by reducing aerodynamic drag , but also improve vehicle stability , reducing any tendency for the vehicle to overturn .