Abstract: Described herein is an engine/pump of a pneumatic type, having a stator with radial cylinders, within which there can slide respective pistons, each carrying a roller that engages an annular cam carried by a rotor. A guide system forces each piston to move, maintaining its axis rigorously aligned with the axis of the respective cylinder. The propulsion system that uses said engine includes high-pressure, medium-pressure and low-pressure tanks, and an auxiliary engine, which controls one or more compressors. A motor vehicle which uses the aforesaid system presents innovative peculiarities as regards construction and location of the tanks of pressurized air or gas, which are filled with spongy material, and also as regards construction of the accelerator and brake controls.