21 October 2014 Last updated at 12:29 GMT

Audi claims self-drive car speed record after German test

By Leo Kelion Technology desk editor

WATCH: The RS7 took a little over two minutes to complete a lap (video filmed by Audi and edited by BBC)

Audi has claimed a speed record for a self-driving car.

The German car giant says its RS7 vehicle topped 149mph (240km/h) while driving uncrewed round the Hockenheim racing circuit, south of Frankfurt.

The car took just over two minutes to complete a lap of the Grand Prix track.

Sunday's stunt was organised to highlight the firm's efforts to bring "piloted driving" to road vehicles. But one expert cautioned that several hurdles still needed to be overcome.

Audi - a division of Volkswagen - also put a human behind the wheel of the vehicle for a comparison lap. He took five seconds longer to complete the circuit.

A member of the car company's research team explained that it believed the innovation could ultimately be used by the public.

"I know accident-free driving will remain a vision. But at least we can reduce the number of accidents in the future," said Dr Horst Glaser.

"Piloted driving defuses situations like, for example, being in a traffic jam. Whenever the driver is distracted and inattentive the car could take over.

"Additionally the driver has a chance to relax. That means they are on full alert as soon as their attention is required again."

Computer equipment in the rear of the car used data gathered from an array of sensors

The RS7 used a combination of cameras, laser scanners, GPS location data, radio transmissions and radar sensors to guide itself around the track, with the data processed by computing equipment that filled its boot.

The experiment marked a high point after 15 years of research by the firm in the US and Europe.

However, one industry-watcher noted that a speed test on an otherwise empty racetrack was very different to the day-to-day driving conditions such vehicles would one day experience.

"I think we will see driverless cars on our roads within a decade, but there's clearly still a lot of work to do," said Prof David Bailey from Aston Business School.

"You need to make sure they interact with other driverless cars as well as those piloted by humans - you've got to make sure the software absolutely works."

He added that the insurance industry also needed to grapple with the concept.

"One of the big issues is what happens if there is an accident," he explained.

"Who is responsible? Is it the driver even if they are not driving? Is it the car company? Is it the software company? There are a whole load of legal issues to sort out.

Mercedes is developing a computer-driven version of its S-class car

"But there could be big savings for the economy in terms of far fewer accidents and more efficient travel."

Audi is far from alone in this field research.

Another German manufacturer, Mercedes, showed off a rival computer-controlled version of its S-class car recently.

Other car companies including Daimler, Volvo, Toyota, Tesla and BMW are also experimenting with artificial intelligence-directed vehicles, as are other tech firms including Google, Panasonic and Autolive.