Invention is a set of automatically or manually inflatable clear mylar bags of specific contour to enhance the aerodynamic efficiency of a rapidly-moving vehicle at speeds where the energy consumption of propulsion is dominated by vehicular wind drag. Whether a motor-vehicle or human-propelled bicycle or other machine, wind-drag losses can exceed 80% of total energy consumption at cruising speeds. This shape-modifier system will inexpensively and safely reduce vehicle design drag losses, allowing for maximum utilization of interior space and minimizing exterior dimensions (in box-shaped vehicles) for low-speed urban transport, but adding airflow drag-reducing streamlining for higher speed travel. Like a falling drop of liquid shaped to the lowest drag coefficient by the forces of air, or similarly inspired by Bucky Fuller's high-efficiency teardrop-shaped Dymaxion low-drag vehicle, the fuel (or effort) savings in many cases will be dramatic.