What self-propelled vehicle did Leonardo da Vinci sketch with springs that stored energy for its movement?

Leonardo da Vinci’s spring-powered vehicle was a self-propelled cart.

Leonardo designed the cart around 1478–1480. Unlike a normal wagon pulled by animals or pushed by people, it was intended to move under its own stored mechanical power. Coiled springs inside the chassis drove the wheels through a system of gears, while a steering mechanism could determine a programmed path.

The cart may have been designed for theatrical presentations at court, where it could appear to move mysteriously without a visible driver. It was not an automobile because it had no internal-combustion engine and could travel only a limited distance before its springs ran down.

A reconstruction displayed at the 2006 Florence Science Festival showed that the concept could function when built from Leonardo’s drawings, though historians and engineers continue to debate details of the original mechanism. The cart is significant as an early example of programmable mechanical motion and stored-energy propulsion.