The vehicle, which operates via the 'Platero' navigation system, has a 50-centimetre margin for error and was test-'driven' on real streets in Madrid.

Thanks to an artificial vision programme, the car is able to recognise the pavement and other obstacles, and its automatic pilot system allows it to simulate a human driver's behaviour and take its own decisions based upon the traffic and the roads.

It made the journey today between the San Lorenzo monastery in El Escorial as far as Arganda del Rey, just east of the capital on the A-3 motorway, escorted by Guardia Civil officers and travelling at an average speed of 60 kilometres per hour.

The Platero programme sends it messages about its position 10 times per second, so that it knows in which direction to head.

Scientists in Madrid have been working on the driverless car for 15 years.