A frame-side air deflector for an automotive vehicle is disclosed. The air deflector includes a first portion oriented substantially vertical with respect to an underside of the automotive vehicle, a second portion oriented substantially perpendicular to the first portion, and a transition portion connecting the first and second portions. In some aspects, the first portion curves outward and away from a centerline of the vehicle and the second portion angles downward from the underside of the vehicle such that as the vehicle travels in a forward direction, air is directed downward, outward, and away from one or more rear-mounted components of the vehicle.