What wheeled machine did Leonardo da Vinci sketch that could move without an animal pulling it?

Leonardo da Vinci sketched a self-propelled cart that could move without an animal pulling it.

The machine, usually dated to the late fifteenth century, used two large driving wheels, smaller stabilizing wheels, and a system of coiled springs. As the springs unwound, they transferred power through gears to the wheels. A steering mechanism allowed the cart to follow a pre-set route rather than being guided continuously by a driver.

Leonardo's drawings do not provide a complete modern construction manual, so details of the original mechanism have been reconstructed from his notes and diagrams. In 2006, engineers at the Institute and Museum of the History of Science in Florence built a working replica based on the surviving design. The replica demonstrated that the basic mechanism could operate.

The cart is sometimes called an early automobile, but that label can mislead. It did not use an engine or fuel; its stored mechanical energy came from springs. Its importance lies in combining stored energy, gearing, steering, and autonomous movement in one Renaissance machine.