While its disengagement rate only fell 0.02 points from 0.20 to 0.18 over the twelve-month period, all these numbers indicate that Waymo is still ahead of its peers. It's done the most extensive testing among all the companies with California permits, and as The Atlantic noted, only GM's Cruise division comes close when it comes to autonomous mileage. Cruise vehicles racked up 125,000 miles on San Francisco's streets without the help of a human driver and reported a yearly average of 1,254 miles per disengagement. We're guessing GM also has plans to expand its testing efforts this year, considering it's aiming to start selling cars without steering wheels in 2019.

Among all the causes of disengagement Waymo mentioned, "unwanted maneuver of the vehicle" topped the list with 19 instances, followed by "perception discrepancy" with 16. It's worth noting, however, that most of those instances happened in the earlier part of the 12-month period, suggesting that the company's technology improved tremendously in the second half of 2017.