What vehicle did Leonardo da Vinci design to move without horses, using coiled springs for power?

Leonardo da Vinci designed a self-propelled cart powered by coiled springs rather than horses.

The design appears in Leonardo’s manuscripts from the late fifteenth century. Two large, symmetrical springs supplied the stored energy, while a system of gears transferred that energy to the wheels. A steering mechanism could be preset, allowing the cart to follow a planned route instead of being driven continuously by a person or animal.

The cart is sometimes described as an early automobile, but that comparison needs care. It did not use an internal-combustion engine, and its spring power would have been limited. It was closer to a mechanical stage vehicle or programmable automaton than to a modern car.

In 2006, engineers at the Institute and Museum of the History of Science in Florence built a working interpretation. The reconstruction demonstrated that the mechanism could move, although surviving drawings leave some details open to interpretation. The invention is notable for combining stored energy, gearing and automatic motion.