What wheeled device designed by Leonardo da Vinci is often called the first self-propelled cart?

Leonardo da Vinci designed a spring-powered self-propelled cart often called the first self-propelled vehicle.

The four-wheeled device appears in drawings from around 1478 to 1480. Coiled springs stored energy and drove the wheels through mechanical transmission, while steering could be programmed with blocks set on a small control drum.

Because the cart could move without being pushed by a person or pulled by an animal, it is often described as an early ancestor of the automobile. It did not have an engine in the modern sense, and its stored spring energy would have limited its travel and power.

The cart's mechanism was reconstructed in the twentieth century, and models demonstrated that the design could move. Some scholars connect it with theatrical stage effects, while others emphasize its importance as an early programmable mechanical device.