What clockwork invention by Leonardo da Vinci is often called the first self-propelled vehicle?

Leonardo da Vinci’s self-propelled cart is often called the first self-propelled vehicle.

Leonardo drew the cart around 1478–1480. Instead of using an engine, it relied on coiled springs mounted inside its body. When wound, the springs released energy through a system of gears and transmitted motion to the wheels. Steering could be set in advance, allowing the cart to follow a predetermined path.

Because it moved without a person or animal pushing it, the cart is sometimes described as an early robot or automobile precursor. However, it was not a motor car in the modern sense: it had no internal-combustion engine, electric motor, brakes, or practical road system. The surviving drawing does not show every construction detail, so modern builders have interpreted some parts differently. A reconstruction made for a 2006 exhibition in Florence demonstrated that the mechanism could work. The cart may have been intended for theatrical effects or court festivities rather than transportation.