The driverless cars that have been heading around California as part of a test run by Google have done so surprisingly efficiently, covering 160,000 miles without incident.

In fact it is only now that one of them has been involved in a prang, but it turns out it was the human being behind the wheel rather the electronic tech working behind the scenes.

The search engine giant confirmed to Business Insider that it was a flesh and blood person who was responsible for the five car pile-up, saying: "Safety is our top priority. One of our goals is to prevent fender-benders like this one, which occurred while a person was manually driving the car."

Experts have said that the technology in the vehicle would have prevented the crash due to its series of sensors and automatic braking systems.

The Toyota Prius was caught on camera in an image sent to US site Jalopnik, and was seen to have crashed into two other Prius hybrids and two Honda Accords. The Google car hit another Prius, which then hit one Honda into another, which in turn struck the third Toyota.