Waymo, the self-driving unit of Google parent company Alphabet, has hit another milestone: 8 million miles driven on public roads. That translates into roughly 25,000 miles driven every day, which is light-years ahead of the company’s competitors and is the result of Google’s very early investment in self-driving technology.

The news was delivered by the company’s CEO John Krafcik on Friday at the National Governors Association in Santa Fe, New Mexico, in an interview with Nevada Gov. Brian Sandoval. Last November, Waymo announced it had driven 4 million miles on public roads, which means the company doubled that number in eight months.

It took eight months to go from 4 million to 8 million miles

Those numbers are only expected to grow as Waymo adds more cars to its fleet of robot taxis. The company currently has over 600 self-driving Chrysler Pacifica minivans operating on public roads. In May, Waymo announced a deal with Fiat Chrysler for an additional 62,000 minivans. And just last week, three of Waymo’s Jaguar I-Pace vehicles hit the road, the first of a promised fleet of 20,000 electric self-driving SUVs.

Waymo has self-driven 8 million miles on public roads, now at a rate of 25K miles per day. This real-world experience, plus over 5 billion miles in simulation, is how we're building the world’s most experienced driver. pic.twitter.com/VkfmLxwi2c — John Krafcik (@johnkrafcik) July 20, 2018

Waymo has also “driven” 5 billion miles in simulation, Krafcik said. That means that every day, over 25,000 virtual versions of the company’s self-driving cars rack up around 8 million miles of simulated driving. The simulator allows self-driving cars to practice situations they may not regularly encounter in the real world. Waymo’s engineers can then run their virtual vehicles through these so-called “edge case” scenarios over and over, accumulating important training data that then gets fed back into the machine learning software.

“There are no autonomous systems available, zero on the road today”

The goal of all this testing is to get to a point where Waymo can launch its first commercial ride-hailing service. The company currently has over 400 residents of Chandler, Arizona, as part of its Early Rider program. Waymo says it is adding more people every day and expects to kick off its paid taxi service later this year.

That said, Krafcik warned the audience that mass adoption of autonomous vehicles will probably be ”longer than you think.” He correctly noted that there are no fully autonomous vehicles available for purchase today, nor will there be for years to come.

“There are no autonomous systems available, zero on the road today,” said Krafcik. “Anything you can buy on the road today is a driver assist system, that means the driver is completely responsible for the car and I think there is so much confusion on that.”