The most reliable self-driving cars belong to Alphabet's Waymo

Boasts lower disengagement rates than Uber, Tesla and others

Alphabet's self-driving car company, Waymo, has shared its results after another year on the road, and it's looking like the Google-powered autonomous driving project is literal miles ahead of the competition.

An autonomous vehicle disengagement report from Waymo sent to the California Department of Motor Vehicles shows the company's self-driving cars have a significantly lower rate of driver intervention compared to others.

Specifically, the report notes Waymo's vehicles clocked an impressive 635,868 cumulative miles of drive time over the past year, but only experienced 124 reported disengagements, or instances where a driver was forced to take over.

Another way of looking at it is that for every 5,128 miles Waymo's self-driving cars traveled, a human only had to step in once. This is even better compared to 2015, as Waymo's disengagement rate dropped by a whopping 75% from 0.8 disengagements per 1,000 miles to just 0.2.

Self-driven performance

While the numbers don't seem that impressive on their own, the rate stands out like a sore thumb when compared to other companies currently honing their self-driving game

BMW, for example, reported just one disengagement in 2016, but only with 638 miles of autonomous driving under its belt. Meanwhile, Nissan reported 28 disengagements over 4,099 autonomous miles (about one disengagement per 146 miles) driven last year. 

Another road marker to Waymo's progress is even further behind. Uber, a newer entrant in the autonomous driving ring, reportedly has a disastrous disengagement rate of one per mile — effectively 5,128 times worse than Waymo's record, according to The Guardian.

It's worth clarifying that Uber's results are from a different source than the California DMV. A representative tells us the company isn't required to produce a disengagement report for the department until January 1, 2018.

While Uber's disengagement rate appears comparatively poor, the company also reportedly put in 20,354 miles' worth of experience last year — more than major manufacturers like Mercedes, Ford, Nissan, BMW and Honda combined. 

(Honda, for example, appears to have not done any testing on public roads in California this year.)

That said, Uber may want to take a note from Waymo to keep its disengagement down for the sake of everyone else on the road — just not literally, as the ridesharing service is already undergoing a lawsuit for allegedly stealing aspects of Waymo's self-driving tech.