Self-driving cars have covered thousands of testing miles on the streets of California, the BBC has reported.

Google has announced that it has been testing the automated vehicles over a distance of 140,000 miles and hopes that the new technology will help reduce crashes and road fatalities in the future.

The vehicles are equipped with cameras, range finders and radar sensors and advanced software allows them to negotiate traffic and busy streets.

Although the testing process has been largely incident free, Google has offered reassurance that the vehicles are only driven over authorised, pre-planned routes and with an operative in the driver's seat ready to take control.