According to Krafcik, Waymo now plans to concentrate on capability, comfort and convenience. Its engineers are reportedly working on new in-house sensing systems, which will help vehicles navigate complex weather conditions, such as rain and snow. It's also working on maneuverability. Krafcik says the company is working on striking the balance between caution and assertiveness, and cited merging lanes in fast-moving traffic as an example of the challenges it faces.

He also says that the company is exploring the relationship between safety and efficiency. "Our cars are designed to take the safest route, even if that means adding a few minutes to your trip ... We value our riders' time, and with even more experience and feedback from people in our cars, we're working on ways to make our routes, pick-ups and drop-offs even more efficient."

Waymo is going through a significant period of growth. It's got plans to bring self-driving taxis to Europe, is in partnership with retail giant Walmart (and could soon be with Uber), has massively expanded its agreement with Chrysler, and has even started moving into China. Its next 10 million miles could be the most eventful yet.