A Waymo self-driving vehicle. Waymo Waymo, the self-driving car company from Google's parent company Alphabet, showed a large improvement in its vehicle testing in 2016, according to a new report published Wednesday by the California DMV.

Waymo reported that it had 0.2 disengagements per 1,000 miles driven in 2016. That's down from 0.8 disengagements per 1,000 miles in 2015.

In the self-driving car world, a "disengagement" is when a human tester has to take over from the automated driving system.

Another promising stat in the report: Waymo's cars drove more miles in 2016 (635,868) versus 2015 (424,331).

In short, Waymo's cars needed a lot less help from their human passengers in 2016. The ultimate goal, obviously, is for Waymo's cars to become fully autonomous.

Companies that are registered to test self-driving cars in California are required to disclose how many disengagements they encounter each year. Only 11 manufacturers, including Honda, BMW, and Ford, are registered. You can read the other disengagement reports here.

Waymo is the newest company under Alphabet's umbrella. It spun out of X, the so-called "moonshot" lab under Alphabet. X has been researching self-driving cars for the better part of a decade and is finally starting to make it a real business through partnerships with traditional car companies like Chrysler. Waymo is also said to be exploring an Uber-like car service for autonomous vehicles.