Picture from the back seat of a Waymo Pacifica minivan while it drives itself on a test route at the former Atwatwer Air Force Base. Picture: Julia Wang / Waymo via AP

Atwater, California - Google's self-driving car spin-off is accelerating efforts to convince the public that its technology is almost ready to safely transport people without any human assistance at all.

Waymo, hatched from a Google project started eight years ago, showed off its progress on Monday during a rare peek at a closely guarded testing facility 200 kilometre southeast of San Francisco. That's where its robots complete their equivalent of driving school.

The tour included giving more than three dozen reporters rides in Chrysler Pacifica minivans traveling through simulated neighborhoods and freeways that Waymo has built on a former Air Force base in the Californian Central Valley city of Atwater.

A driverless Waymo Pacifica minivan stops for company staffers cycling and walking in a simulated neighbourhood at the former Atwater Air Force Base. Picture: Julia Wang / Waymo via AP

The minivans smoothly cruised the roads - driver's seat empty and passengers in the back - at speeds of up to 55km/h. By contrast, the Waymo-powered Pacifica minivans that have been driving volunteer riders around Phoenix, Arizona, still use safety drivers to take over control if something goes wrong.

But Waymo's real goal is to the point where people in cars are nothing but passengers. CEO John Krafcik told reporters that the company would be making some cars and trucks totally driverless fairly soon, though he didn't provide a specific timetable.

"We are really close," he said. "We're going to do it when we feel like we're ready."

A driverless Waymo Pacifica minivan avoids a group of company staffers unloading boxes on a test route at the former Atwater Air Force Base. Picture: Julia Wang / Waymo via AP)

Since Google began working on self-driving cars in 2009, dozens of established automaker such as General Motors and Ford have entered the race, along with other big technology companies, including Apple and ride-hailing service Uber. 

The competition is so fierce and the stakes so high that Waymo is hoping to infuse its technology into ride-hailing services such as its current partner, Lyft, and big-rig trucking companies. It also intends to license its automated system to automakers such as Fiat Chrysler Automobile, which is already using it in 100 Pacifica minivans.