What Leonardo da Vinci invention was a four-wheeled cart that moved by stored spring power?

Leonardo da Vinci designed a self-propelled cart that moved by stored spring power.

The cart, drawn in a late-fifteenth-century manuscript, used coiled springs to provide motion instead of an external animal or person. Its mechanism also included programmable features: pegs on wheels could determine a sequence of movements, and steering could be set for a curved route.

The invention is often called Leonardo's car, but it was not an automobile in the modern sense. It had no combustion engine, electrical motor, or passenger cabin. Its purpose may have been theatrical, perhaps to move automatically during a court celebration, although the exact intended use is uncertain.

A working replica built in 2006 demonstrated that the design could move when reconstructed with modern interpretation. The cart is important because it shows Leonardo combining mechanical power, steering, and limited programmability several centuries before motor vehicles became practical.