Volvo has tested a convoy of a lorry and three self-driven cars over 200km on a Spanish motorway, in what is the first ever public test of self-driven vehicles.

The company performed the test as a part of the European Commission research project known as Sartre – Safe Road Trains for the Environment, which has been underway since 2009.

During the test, the company connected the three cars to each other using a wireless autonomous control and then to a leading lorry, driven by a professional driver.

Volvo Car Sartre project manager Linda Wahlstroem said that driving among other road-users is a great milestone for the project.

"We covered 200km in one day and the test turned out well. We’re really delighted," Wahlstroem added.

"People think that autonomous driving is science fiction, but the fact is that the technology is already here. From the purely conceptual viewpoint, it works fine and road train will be around in one form or another in the future."

"We’ve focused really hard on changing as little as possible in existing systems. Everything should function without any infrastructure changes to the roads or expensive additional components in the cars."

"Apart from the software developed as part of the project, it is really only the wireless network installed between the cars that set them apart from other cars available in showrooms today."

The trailing cars are equipped with cameras, radar and laser sensors, which allow them to follow and mimic the lead vehicle move.

The cars, which maintained a gap of 6m from each other, accelerated, braked and turned in the same manner as the leading lorry was driven.

The other project partners include car technology firm Ricardo UK, Tecnalia Research & Innovation of Spain, Institut fur Kraftfahrzeuge Aachen (IKA) of Germany and the Technical Research Institute of Sweden.