A drag reducing device for a commercial vehicle. The drag reducing device includes a rectangular frame having a pair of hinged sections. The frame is securable to the rear of the commercial vehicle and is sized so as to cover approximately half of the rear of the vehicle. The frame can be unfolded so that the hinged sections are arranged in the same plane and such that the frame covers the rear of the vehicle. The frame supports an inflatable member thereon, wherein the inflatable member is shaped such that it tapers towards a point at a rear portion thereof. The inflatable member substantially covers the rear of the tractor trailer when in use. Optionally, a control unit is provided for remotely inflating or deflating the inflatable member, wherein the control unit operates an air pump disposed within the frame.