Residents in the US city of Pittsburgh began using the new technology under Uber's self-driving pilot program.

Automotive industry executives remain sharply divided over a timeline for a full roll-out of the technology, with some expecting fully autonomous cars within five years and others predicting they are still decades away.

The Pittsburgh pilot is the first time self-driving cars have been so freely available to the public.

Four self-driving vehicles will be made available to passengers, to start, but two people will sit in the front to take-over driving when the car cannot steer itself.