Waymo, Alphabet's autonomous vehicle division, has driven more than 4 million miles, the company announced in a blog post on Tuesday.
Furthermore, in simulations, Waymo's cars have driven more than 2.5 billion miles.
Since Waymo split from Google in late 2016, becoming a company in its own right under parent Alphabet, the rate of research and development seems to have accelerated considerably. It took six years to reach 1 million miles, and almost 18 months to reach 2 million, but the company covered 2 million miles in just over a year. (See Google's Waymo Could Be Worth $70B by 2030 – Analysts.)
It took Waymo only 6 months to go from 3 million to 4 million miles. Image: Waymo
In addition, the company's cars have driven through 23 US cities, in four states: Washington, California, Arizona and Texas. Naturally, the company has a lot more to test and scenarios to play out, but knowing they've tested in some of the busiest and most congested cities in the US -- San Francisco, Austin and Phoenix among them -- augurs well for the future of autonomous technology.
Waymo also tests on its private, 91-acre test facility, creating unique scenarios for its cars to navigate. The benefit of this is that, naturally, Waymo can test a specific scenario (such as a particularly hard to navigate junction, or put the cars up against aggressive or bad drivers) over and over again, training the cars in that instance.
Waymo's cars have driven in 23 US cities over 4 states. Image: Waymo
Finally, Waymo notes that its cars have driven over 2.5 billion miles in simulation. Simulation driving is the same as normal driving for the cars; the software sees it as no different, and so can test the scenarios as it would in the real world, but with thousands of cars -- which all increases Waymo's rate of learning about self-driving cars. (See How Waymo Uses a Virtual World to Train Its Cars.)