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What is California’s Best Self-Driving Car?

autonomous cars in California, disengagement rate, 2019 disengagement rates, Waymo’s autonomous cars, autonomous car companies

California’s DMV just made public the 2019 disengagement rates for the state’s autonomous car companies. Disengagement refers to when a self-driving car cedes authority to its human occupant. The moment a human takes the wheel, the car has been disengaged. Therefore, a disengagement rate measures how many times a car disengages per 1,000 self-driven miles. Waymo, out of Mountain View, has the lowest disengagement rate of all California-based autonomous car companies that logged at least 1,000 miles. However, other makes are close behind, including Tesla, whose autonomous fleet is few in number but perfect in the score.

Waymo’s Supremacy

Waymo’s autonomous cars, which number 153 in California, drove 1.45 million miles across the state in 2019 and registered a disengagement rate of 0.076. That’s one disengagement per 13,219 miles. Along with achieving the best rate for a California-based autonomous carmaker, Waymo holds the record for most miles driven in California by an autonomous fleet.

Cruise Cruises to Second

Cruise is a subsidiary of General Motors that uses the car consumer report-approved Chevrolet Bolt to autonomously shuttle people around the Bay Area. Its 233 vehicles drove 831,040 miles in 2019. In driving all those miles, it experienced 68 disengagements – a rate of 0.082 per 1,000 miles. That’s one disengagement per 12,221 miles.   

Other Makes

Other autonomous car companies that clocked significant time on California’s roads include Nuro, whose 36 vehicles drove 68,762 miles for a disengagement rate of 0.49, and Aurora, which, because of a software issue, registered a disengagement rate of 10.6 per 1,000 miles. Baidu, a Chinese company with four California-licensed autonomous vehicles, scored even higher than Waymo. The four cars traveled 108,300 miles in 2019 and suffered only six disengagements. That’s a rate of 0.055. Rounding out the list of autonomous car companies with at least 10,000 California miles driven are Apple, Zoox,, and Lyft.   

Honorable Mention: Tesla

Tesla’s 32 self-driving California cars didn’t register a single disengagement in 2019. Yes, that’s a rate of 0.00. However, these cars combined for just 12.2 miles. Like Barry Bonds, Tesla has an asterisk next to its high score.

All California autonomous car companies are compelled to report their disengagement rates to the DMV. While the disengagement metric has been criticized for not accurately capturing autonomous performance, it’s the best judge we have at the moment. The judge has spoken: Waymo is the most reliable autonomous car company in California, although both Baidu and Tesla have lower disengagement rates with fewer miles driven.

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