What Leonardo da Vinci invention could move without being pushed, using springs and gears?

Leonardo da Vinci designed a self-propelled cart powered by wound springs and controlled by gears.

The cart appears in a drawing from the late 15th century and is commonly treated as an early ancestor of the automobile. Its springs stored mechanical energy, while a system of gears transmitted that energy to the wheels. Programmable control was provided by shaped cams, allowing the cart to follow a predetermined movement rather than being steered continuously by a driver.

The device was not an automobile in the modern sense. It carried no engine, fuel tank, or steering system for ordinary roads, and surviving evidence does not show that Leonardo built it himself. Modern reconstructions have demonstrated that the mechanism can move when constructed from the drawing.

The cart is also called Leonardo's automobile, but “self-propelled cart” is the clearest description of the original spring-driven machine.