LOS ANGELES - With its eight hairpin turns negotiating a hair-raising 31.5 per cent gradient, San Francisco's Lombard St is one of the toughest tests drivers can face.

But if Google has anything to do with it, soon they will be able to just sit back and let the car do the work.

Filling a vehicle with enough technology to make a James Bond car look humble, the internet giant has developed a car that can drive itself.

Seven modified Toyota Priuses and an Audi TT have already clocked up 225,000km while driving along the roads of California, taking in not only San Francisco's most famous road but also the Golden Gate Bridge, Hollywood Boulevard in Los Angeles and the Pacific Coast Highway.

The vehicles look much the same as others on the road, apart from chimney-like cylinders mounted on brackets above the roofs that act as the cars' eyes.

They use a system of video cameras, radar sensors and laser range-finders to detect other vehicles, while following a pre-set route mapped out by drivers in ordinary cars.

The software controls acceleration and deceleration, while the cameras read and interpret traffic lights and other signs.

Google says only one minor accident took place, when one of the cars received a bump from behind at traffic lights.

Sebastian Thrun, a co-inventor of Google's Street View mapping service and director of the Stanford Artificial Intelligence Laboratory, blogged that Google is developing the car primarily in the hope that it will improve traffic safety.