Abstract: A portable, collapsible air flow deflection apparatus detachably connectable to the roof of a motor vehicle for diverting air flow above and to the sides of the frontal surface of a vehicle in tow behind the motor vehicle. A pair of triangular, planar rigid panels are hinged along common edges and are relatively positioned at an angle thereabout to provide a V-shaped member. An internal planar frame cooperatively engages the hinged panels to fix the shape of the deflection member. Adjustable hold-down means secured to the frame compressively anchor the deflection member to the motor vehicle roof in an upright orientation, presenting a wedge-shaped deflection surface toward the front of the motor vehicle. Hinged and resilient portions along the lower edges of the deflection member adjust to the contour of the motor vehicle roof for presenting a continuous air deflection surface therewith.