A deflector mounts to a pickup truck. The deflector may include a mounting flange, mounted to and pivot with a bottom of a tailgate, and spaced from a rear bumper, and a louver extending downward from the mounting flange into a gap between the tailgate and the bumper, with the louver including a portion curving rearward as the louver extends downward such that air flow around the bumper from under the pickup truck is redirected upward along an outer panel of the tailgate.