What propulsion system did Leonardo da Vinci design for a self-propelled cart?

Leonardo da Vinci’s self-propelled cart used clockwork springs for propulsion.

The cart appears in a drawing from around 1478–1480 and is often described as an early programmable vehicle or ancestor of the automobile. Two large leaf springs stored energy, while a system of gears transferred that energy to the wheels. A steering mechanism allowed the cart to follow a predetermined path, making it useful for theatrical displays or court ceremonies.

Leonardo did not use a motor in the modern sense, and the cart was not designed for long-distance transport. Its springs had to be wound before operation, much like the mainspring in a clock. In 2006, a replica built by the Museo della Scienza e della Tecnologia in Milan demonstrated that the mechanism could move. The cart is therefore best understood as a spring-powered automaton, not a petrol, steam, or electric car.