Leonardo's car springs into life after lying on drawing board for 500 years

So this is where we went wrong. Here is the fork in the road. More than 500 years before politicians and environmentalists wrestled with the threats and appetites of the SUV, Leonardo da Vinci showed us the way to go: an automobile made of wood, controlled by the world's first computer, and consuming the cheapest fuel in the world, elbow grease.

So this is where we went wrong. Here is the fork in the road. More than 500 years before politicians and environmentalists wrestled with the threats and appetites of the SUV, Leonardo da Vinci showed us the way to go: an automobile made of wood, controlled by the world's first computer, and consuming the cheapest fuel in the world, elbow grease.

After several fruitless attempts, experts in Leonardo studies and robotics have finally worked out how the Leonardo automobile was intended to function. This week a full-size model of the car was on show in the Museo Leonardiano, in the Tuscan village of Vinci where the genius was born.

But it is unlikely to catch on. For a start, there is nowhere to sit; it seems the vehicle was conceived for Renaissance court theatrical performances, to amaze and delight the local lords and ladies with the sight of a vehicle trundling along, turning corners and coming gently to a halt with no human involvement of any sort. In conception, the vehicle is closer to the sort of wheeled robots that whiz around Japanese factories, fetching and carrying, than to a passenger-bearing car.

It has three wheels, two at the front and one at the back, so with the operator perched on it setting the navigation system it looks like an over-size Stone Age ice-cream cart.

The motive power is familiar to any child: you coil the springs that drive it forward by pushing the vehicle backwards. You then secure it with a rope, waiting for the cue to let fly.

The discovery of how Leonardo intended the vehicle (found on page 812R of his Atlanticus Codex) to work was slow and tortuous. For many years researchers thought the motive power came from two big leaf-springs on the top of the vehicle. But when they constructed scale models based on that interpretation, they refused to budge.

The breakthrough came when Carlo Pedretti, director of the Armand Hammer Centre for Leonardo Studies in Los Angeles, poring over copies from the Uffizzi archives of sketches by Da Vinci showing the vehicle from above, twigged that the problematic springs were not intended to drive the car but to control its navigation.

The motive power, Professor Pedretti decided, came from springs contained in two drum-like casings on the vehicle's underside. This intuition was endorsed by Mark Rosheim, an American robotics expert.

Digital models were constructed on a computer to test the vehicle's viability; when they appeared to work, Professor Paolo Galluzzi, director of the Institute and Museum of the History of Science in Florence, who was in overall control of the project, approached Florentine wood craftsmen to get a model built for real, using materials that were available in the 15th century. That meant five different types of wood, the hardest being reserved for the car's cogs.

"This carriage," Mark Rosheim said, "can be considered a precursor of mobile automatons, and perhaps, indeed, the first computer ever built in Western civilisation". Readers who have got this far will have gathered that the car was not intended for Da Vinci family jaunts in the Tuscan countryside. Its range, in fact, was only about 36 yards before it required rewinding. After the navigation had been programmed and the restraining rope released, the vehicle was its own master.

Paolo Galluzzi believes that "most probably" an early prototype of the vehicle was built, but the finished work remained locked in the pages of Da Vinci's notebooks, its springs tightly wound since 1478, waiting to be unleashed on the world.

But that was true of most of his extraordinary conceptions, including helicopter, tank, submarine, multi-barrel machine-gun. At one scale or another. most have now been realised, and been put on show in the museum in the village of Vinci, which celebrates its expansion this week with the unveiling of the Leonardo car.

Romano Nanni, the museum's director, said: "As Leonardo became older, he dedicated more time to mechanical sketches and doodles than to art." Other visions that flowed from his pen included a parachute, a suspension bridge, a mechanical calculator, and a solar heater, using mirrors to warm water.

One idea, perhaps uniquely, seems to have inspired technological development in his own lifetime: a machine called the "gold-beater" in which a hammer controlled by gears pounds a bar of gold held in a protective sheath to produce gold leaf for picture frames. Unlike many of Leonardo's other visions, the car, it has now been proved, would actually have gone places, stunning and delighting anyone lucky enough to clap eyes on it.

But anyone unlucky enough to be in its pre-programmed path would have been flattened. That is why Leonardo One has yet to make its maiden voyage: they do not dare risk it.