What type of transport did Leonardo da Vinci design with a spring-powered mechanism in its chassis?

Leonardo da Vinci designed a self-propelled cart with a spring-powered mechanism in its chassis.

The cart is usually dated to the late fifteenth century and is described in Leonardo's studies of mechanical engineering. Its movement came from coiled springs, much like the power source in a large clockwork mechanism. Cams and other components could be arranged to control the cart's motion and steering.

The design may have been intended for theatrical performances or court spectacles rather than ordinary transportation. A hidden operator or mechanism could make the cart appear to move on its own, creating a dramatic effect for an audience.

The cart is sometimes called an early automobile, but that comparison is only approximate. It had no engine, fuel system, or modern road controls. It should also be distinguished from Leonardo's human-powered vehicle concept, which relied on people rather than stored spring energy.