The head of self-driving cars for Google expects real people to be using them on public roads in two to five years.

Chris Urmson says the cars would still be test vehicles, and Google would collect data on how they interact with other vehicles and pedestrians.

Google is working on sensors to detect road signs and other vehicles, and software that analyzes all the data.

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Google is talking to car giants including General Motors Co, Ford Motor Co, Toyota Motor Corp, DaimlerAG and Volkswagen AG in a bid to bring self driving cars to the road in 2020.

The small, bulbous cars without steering wheels or pedals are being tested at a Google facility in California.

Urmson wouldn't give a date for putting driverless cars on roads en masse, saying that the system has to be safe enough to work properly.

He told reporters Wednesday at the Automotive News World Congress in Detroit that Google doesn't know yet how it will make money on the cars.

Urmson wants to reach the point where his test team no longer has to pilot the cars.

'What we really need is to get to the point where we're learning about how people interact with it, how they are using it, and how can we best bring that to market as a product that people care for,' he said.

Google may face state regulatory hurdles depending on where it chooses to test the cars in public. Under legislation that Google persuaded California lawmakers to pass in 2012, self-driving cars must have a steering wheel and pedals.

Several other states have passed laws formally allowing autonomous cars on public roads without that restriction.

The company in December announced that it had a fully functioning prototype that's been driving on its test track.

The small, bulbous cars without steering wheels or pedals are being tested at a Google facility in California.

It hoped to see the cars on the road in northern California this year, but they would have to have safety drivers and temporary manual controls.

Google also confirmed that it has hired Roush Enterprises Inc., a Detroit-area company that designs and builds prototypes for the auto industry, to build 150 prototype Google autonomous cars.

Urmson said Google is making laser and other sensors for the cars smaller and less costly.

He predicted that the cars would fail at some point on public roads, but said Google's cars have been driven more than 700,000 miles on public roads without causing a crash.

Google has begun discussions with most of the world's top automakers in a bid to get self driving cars on the road by 2020.

'We'd be remiss not to talk to ... the biggest auto manufacturers. They've got a lot to offer,' Chris Urmson, director of Google's self-driving car project, said.

HOW DOES GOOGLE'S AUTONOMOUS CAR WORK? Google's prototype two-seater 'bubble' cars have buttons to begin and end the drive, but no other controls. An on-board computer uses data from sensors, including radar, a laser and cameras, to make turns and negotiate its way around pedestrians and other vehicles. Under the vision unveiled by Google, passengers might set their destination by typing it into a map or using commands. The cars are also expected to be electric, capable of going 100 miles (160 km) before needing to be recharging. The front of the vehicle has a soft foam-like material where a traditional bumper would be and a more flexible windscreen, in an attempt to be safer for pedestrians. The prototypes are restricted to speeds of 25mph (40 km/h) and the ability to self-drive will depend on specifically designed Google road maps tested on the company's current fleet of vehicles. But ultimately the vehicles will be faster and will be able to use Google's extended maps service, using GPS technology to locate the vehicle's exact position on an electronic map. A combination of radar, lasers and cameras sitting on top of the roof give the car a 360-degree 'view', with sensors linked to computer software able to 'see' and identify people, cars, road signs and markings and traffic lights. Advertisement

Those manufacturers, he said, include General Motors Co, Ford Motor Co, Toyota Motor Corp, DaimlerAG and Volkswagen AG.

'For us to jump in and say that we can do this better, that's arrogant,' Urmson said.

Google has not determined whether it will build its own self-driving vehicles or function more as a provider of systems and software to established vehicle manufacturers.

Google's self-driving prototype cars, he said, were built in Detroit by engineering and specialty manufacturing company Roush.

GM is open to working with Google on self-driving cars, Jon Lauckner, GM's chief technology officer, said on Monday.

Urmson's expectation that the first fully autonomous vehicles will be production-ready within five years mirrors the view expressed a day earlier by another Silicon Valley entrepreneur, Elon Musk, chief executive of Tesla Motors Inc .

Musk, who spoke Tuesday at the Automotive News World Congress conference, said he expects the lack of clear federal regulations covering self-driving cars could delay their introduction until 2022 or 2023.

Urmson, however, said his Google colleagues 'don't see any particular regulatory hurdles.'

Google has been briefing the National Highway Traffic Safety Administration, the chief U.S. auto regulator, 'from early on in our program,' Urmson said. 'The worst thing we could do is surprise them.'

Google has already adapted cars to include its self driving technology

Urmson said Google is developing and refining self-driving systems and components with such auto parts suppliers as Continental AG, Robert Bosch, ZF and LG Electronics. Google's prototype cars use microprocessors made by Nvidia Corp, a Silicon Valley chipmaker that also supplies Mercedes-Benz and other automakers.

Continental said it began discussions in 2012 about supplying parts for Google's self-driving car. Google asked the German supplier to provide tires, some electronics and other components, according to Samir Salman, chief executive of Continental's NAFTA region.

Google shortly will begin deploying a test fleet of fully functioning prototypes of its pod-like self-driving car, which dispenses with such familiar automotive parts as steering wheel, brakes and accelerator pedal.

While each of the Google prototypes will have a 'test driver' on board, the cars have no provision for human intervention in steering or braking.

Urmson suggested the no-frills look of the Google prototypes, a far cry from the opulent appearance of the self-driving F015 concept vehicle unveiled last week by Mercedes, does not necessarily reflect the final design for production.

He described the Google prototype as 'a practical, near-term testing platform' that will evolve over time.

'Airliners today don't look like the Wright brothers' flyer' of 100 years ago, he said.

Urmson said self-driving cars represent a 'transformative' moment in the evolution of transportation, an opportunity to extend motoring to blind, elderly and disabled persons who otherwise could not drive.

'You're really changing the relationship you have with transportation. You're changing what it means to get around.'

Regarding Google's desire to partner with traditional automakers and suppliers, Urmson said Detroit is more innovative than is sometimes acknowledged. Automakers are 'doing something incredibly complicated.'