What self-propelled machine did Leonardo da Vinci design using springs to drive its wheels?

Leonardo da Vinci designed a self-propelled cart using wound springs to drive its wheels.

The machine appears in drawings made around 1478–1480. Two symmetrical leaf springs stored energy, while gears transferred that energy to the wheels. A steering system could be preset, allowing the cart to follow a programmed path rather than being guided continuously by a driver.

The cart was probably intended for theatrical displays or court spectacles. It was not a practical automobile: its springs offered limited energy, its route was constrained, and it had no engine or braking system comparable to those in modern vehicles. Nevertheless, its combination of stored power, gearing, and programmable steering is technically remarkable.

A full-scale replica was built and demonstrated in Italy in 2006 by researchers and engineers studying Leonardo’s drawings. The machine is often called Leonardo’s automobile, although “self-propelled cart” more accurately describes the Renaissance mechanism.