What type of vehicle did Leonardo da Vinci design with a spring-powered self-propulsion mechanism?

Leonardo da Vinci designed a spring-powered self-propelled cart.

The machine appears in drawings from around 1478–1480 and is sometimes called the earliest predecessor of the automobile. It used coiled springs to store energy, while a system of gears transferred that energy to the wheels.

A steering mechanism allowed the cart to follow a predetermined route. This made it useful as a theatrical device or ceremonial machine rather than as a practical road vehicle for carrying people over long distances.

The cart was not powered by an engine and did not use fuel. Its importance is mechanical: it demonstrates Leonardo’s understanding of stored energy, gearing, timing, and controlled motion. Reconstructions have shown that the design can move when built according to the surviving drawings, though some details remain open to interpretation.