Which Leonardo da Vinci invention is a cart that moves using coiled springs?

Leonardo da Vinci’s cart that moves using coiled springs is known as the self-propelled cart.

Leonardo designed the cart around 1478–1480, making it one of his earliest mechanical projects. Two symmetrical leaf springs stored energy and drove the wheels through a system of gears. A steering arrangement allowed the vehicle to follow a predetermined route rather than being freely controlled like a modern car.

The cart was probably intended for theatrical or ceremonial use. It could have carried a small figure or moving display during a court performance, rather than transporting people over roads. Its mechanism was hidden inside a wooden body, which helped create the impression of an autonomous object.

The cart is often called the first automobile, but that description needs qualification. It was a spring-powered automaton, not a practical road vehicle with an engine, brakes, and adjustable steering. Reconstructions have shown that the basic mechanism can work, although surviving drawings leave some details open to interpretation.