What transport invention did Leonardo da Vinci design with four wheels and a spring-powered mechanism?

Leonardo da Vinci designed a self-propelled cart with four wheels and a spring-powered mechanism.

The cart appears in drawings from around 1478–1480 and is often described as an early programmable machine. Coiled springs supplied energy, while gearing transferred that energy to the wheels. Adjustable cams helped determine the cart’s movement, allowing it to follow a planned path rather than being pushed continuously by a person.

The device may have been intended for theatrical performances, court celebrations, or stage effects. It was not an automobile in the modern sense: it carried no engine, steering wheel, or driver. A reconstruction displayed at the 2006 Florence Science Festival demonstrated that the mechanism could move when built according to Leonardo’s drawings.