What Leonardo da Vinci invention was a self-propelled cart powered by coiled springs rather than horses?

Leonardo da Vinci's spring-driven vehicle was a spring-powered cart.

Leonardo designed a self-propelled cart whose motion came from coiled springs mounted inside the vehicle. Gears transferred the springs' stored energy to the wheels, while a steering system helped guide the cart. The mechanism resembles a large clockwork device scaled for transport.

The cart is often called an early automobile, but it lacked an internal-combustion engine and was not intended for ordinary long-distance travel. Its likely role was theatrical or ceremonial, where a vehicle could move across a stage or court setting without a horse visibly pulling it.

A full-scale reconstruction was built in the twenty-first century using Leonardo's drawings and demonstrated that the design can move. The reconstruction does not prove every detail of the original plan, but it confirms that the central spring-and-gear principle is mechanically plausible.