What mechanical device did Leonardo da Vinci design to move itself using stored spring energy?

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

The cart appears in drawings from the late fifteenth century and is often described as an early ancestor of the automobile. Unlike a modern vehicle, it did not use an engine or fuel. Coiled springs stored energy, while a system of gears transferred that energy to the wheels. The design also included programmable control features using pegs on rotating drums, allowing the path of the cart to be set in advance.

The cart may have been intended for theatrical spectacles at court rather than transportation. It could reportedly travel for a limited distance and perform a controlled movement, making it useful as a stage effect. Its exact original construction remains uncertain because Leonardo’s surviving drawings are incomplete and technical interpretations differ.

The device is sometimes confused with Leonardo’s mechanical lion or robot knight. Those were separate projects. The cart is specifically notable for self-propulsion through spring-driven clockwork.