What self-moving vehicle did Leonardo da Vinci sketch without an onboard driver?

Leonardo da Vinci sketched a self-propelled cart that could move without an onboard driver.

The machine appears in drawings from the late 15th century and is powered by coiled springs hidden inside its body. As the springs unwind, they drive the cart’s wheels through a mechanical transmission. A steering system could be set in advance, allowing the vehicle to follow a predetermined path rather than respond to a driver.

The cart was probably intended for theatrical or ceremonial use, such as producing a dramatic moving effect at a court event. It was not an automobile in the modern sense: it had no combustion engine, electric motor, or system for steering freely while moving.

Because the original mechanism is incomplete in some details, reconstructions have tested different interpretations of Leonardo’s drawings. The basic principle is nevertheless clear: stored spring energy powered a programmable wheeled device.