Embodiments of the disclosure provide a foldable/retractable and unfoldable/deployable, rearwardly tapered aerodynamic assembly for use on the rear trailer bodies and other vehicles that accommodate dual swing-out doors. The aerodynamic assembly includes a right half mounted on the right hand door and a left half mounted on a left hand door. Each half can be constructed with a side panel, top panel and bottom panel, which each form half of an overall tapered box when deployed on the rear of the vehicle, the bottom panels and top panels being sealed together at a pair of overlapping weather seals along the centerline.