Leonardo da Vinci’s four-wheeled vehicle is known as the self-propelled cart.
The cart was designed around 1478–1480 and used coiled springs to store energy. When released, the springs drove a system of gears that turned the wheels. A steering mechanism also allowed the vehicle to follow a preset path, making it more than a simple wagon.
Leonardo may have intended the cart for theatrical performances or court spectacles rather than transportation. It had no internal-combustion engine and was not an automobile in the modern sense. Reconstructions have shown that the mechanism can work when built according to the surviving drawings, although historians continue to study details of its original operation.