Google X head of public policy Sarah Hunter told the International Transport Forum (ITF) summit in Leipzig that software advances and the rate of processing of data from vehicle sensors offered the next step.
"My own view is that software offers a really great technological breakthrough."
Hunter said more sedate bubble cars now being road tested by Google are the future specifically.
"I'm often asked what automation means — the Hollywood version is not the truth, the robot car you see in The Jetsons, The Terminator or Star Wars is not what automation means to me."
For Google, fully autonomous cars (or planes) just require a destination command.
"It can take you from A to B without you ever having to be involved," she said. "It's so autonomous it doesn't need brakes or a steering wheel."
Road accidents are a leading cause of death, with about 3500 people a day dying worldwide, and more than 90 per cent of accidents caused by human error.
She said human error also caused most aircraft crashes.
Systems driving autonomous vehicles had the benefit of never getting tired or distracted by text messages.
"We're pretty confident we can make a difference to these [crash] statistics," Hunter said.
"We have to be realistic we're not going to remove accidents from the street but we have to keep in mind the bigger picture."
ITF studies have concluded that a further radical shift would be achieved by the widespread adoption of sharing autonomous cars.
Up to nine out of 10 conventional cars could become redundant under certain circumstances.
"Vast amounts of public space would be freed up for other uses in such a scenario," the ITF said.
While a potential benefit of more automated driving is improved road safety, 99.9 per cent of driving by humans involved no crashes.
The test for autonomous cars will be how well they can replicate the crash-free performance of human drivers. Results from early prototypes are promising, but new types of crashes may emerge, such as during hand-over of control, when a computer gives the human occupant just seconds to react.
Full automation could be reached via two development paths — the first involving gradually improving automation in conventional vehicles, where human drivers can shift more of the driving task to these systems.
The second involves introducing cars without a human driver in limited situations — such as particular routes and low-speed operations — and then gradually expanding use.
The first path raised difficult issues of human-machine interaction, because the human must resume active control when prompted.
Self-driving cars could shake up the transport system. If deployed in fleet-wide systems, that would fundamentally reshape travel and impact on public transport and taxis.
The ITF research found that at a minimum, autonomous vehicle regulation should ensure safety and prevent market failures. "Yet, codifying requirements at an early stage can also cause the legal framework to lag, not lead. Some regulatory flexibility seems desirable — for instance allowing circumscribed uses, such as low-speed urban operation or motorway [use], before implementing a blanket set of rules," it said.
Google earlier this month announced it would begin testing a new line of its autonomous vehicles, bringing as many as 25 new custom-built self-driving cars to Mountain View streets. The bubble-shaped cars are the latest model developed by the company and follow an earlier test of about 20 Lexus SUVs equipped with self-driving software, logging about 16,000km a week. Reports say the Google team has done more than 1.6 million km of road driving the past 18 months, and in 11 crashes the fault lay with human motorists.
California regulators are currently working on new rules for enforcement and liability issues.
— Grant Bradley is in Leipzig courtesy of the International Transport Forum.
