What Leonardo da Vinci invention was a spring-powered cart that could move without being pushed?

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

The compact machine, usually dated to around 1478–1480, used stored energy in coiled springs to drive its wheels through a system of gears and mechanisms. Leonardo may have intended it for theatrical performances, where a cart could move across a stage without an obvious person pushing it. Its operation would have been limited by the energy stored in the springs and by the precision of its mechanism.

The cart was not powered by steam, gasoline, or electricity. It is therefore not a motor car in the modern sense, even though its self-moving action resembles that of a vehicle. The design is also separate from Leonardo's later mechanical lion and other automata.

A reconstruction built for a 2006 exhibition in Florence showed that the concept could work when made with historically plausible materials. The cart is often celebrated as an early ancestor of the automobile, but that description is only a comparison; it did not provide continuous engine power or practical transportation.