Ready for a completely driverless taxi cab? Riders in the Phoenix area will have the chance to summon a fully autonomous, self-driving vehicle when Google's Waymo launches its ride-sharing service later this year, the company announced.

Waymo launched a pilot program last year, but has until now relied on vehicles that still have “operators” ready to take control in an emergency. And volunteers got to use the service for free. With the approval of Arizona regulators, it will soon start charging riders who will be able to summon a vehicle using a smartphone app, much like competitors such as Uber and Lyft. Those new vans will operate driverlessly.

“As we continue to test-drive our fleet of vehicles in greater Phoenix, we’re taking all the steps necessary to launch our commercial service this year,” a Waymo spokesman said.

In a deal announced last month, Waymo said it plans to add “thousands” of completely driverless Chrysler Pacifica Hybrid vans that will start serving Phoenix and then expand into other U.S. markets.

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While specific details have yet to be released, Waymo could sharply undercut its competition on pricing, as drivers make up the biggest line item when it comes to operating costs for ride-sharing and taxi services. That’s why it costs about $1.40 a mile to use a service like Lyft, compared to an average $0.80 a mile to own and operate a personal car, said Gill Pratt, the head of the Toyota Research Institute, which is developing that automaker’s driverless technology.

Many experts believe that by switching to driverless vehicles, ride-sharing services will drop their prices enough to allow millions of U.S. motorists – especially those in urban centers – to sell off their cars. As much as 20 percent of the miles Americans clock on the road each year will be in driverless ride-sharing vehicles, according to a study released last December by the Boston Consulting Group.

Some recent studies have put the number significantly higher and former Ford CEO Mark Fields, a high-profile proponent of the technology, told NBC News that U.S. new car sales could taper off as driverless vehicles become more commonplace.

Toyota and Ford are working on their own driverless technologies and have expressed interest in entering the “mobility services” field as a way to compensate for that potential decline in traditional sales.

General Motors is also pressing into the field and is waiting for federal approval to start testing a completely driverless version of its Chevrolet Bolt battery-electric vehicle.

While GM has not specifically outlined its plans, it is widely expected it will use some of those vehicles in its own Maven vehicle-sharing service, and possibly provide others to Lyft, the ride-sharing service in which it now owns a large stake.

Many experts will be watching to see what sort of business case Waymo can make. Its key ride-sharing competitors have so far been operating deep in the red, so cutting the driver out of the picture could help turn the bottom line black.

But there is also concern about the safety of driverless technology. Joan Claybrook, the former head of the National Highway Traffic Safety Administration, last month called upon state and federal regulators to slow down the push to test and commercialize autonomous and fully driverless technologies on public roads.

Critics note that there have been a number of crashes involving self-driving technologies, including around 20 at Waymo, though only one has so far been blamed on the company’s vehicles. Uber has had several crashes and two separate federal safety agencies sent investigators to California last month to probe a crash of a Tesla Model S reportedly operating in semi-autonomous Autopilot mode. That system took much of the blame for an earlier, fatal crash in Florida.

But Waymo officials insist they are confident they can operate safely. Its various prototype and pilot vehicles have already clocked “more than 4 million miles test driven in the real world in seven states (and) 25 U.S. cities,” said Ruth Porat, CFO of parent company Alphabet, adding that Waymo is logging another 10,000 miles daily while continuing to clock “billions of miles” in its computer simulators.