Tesla Is Testing Self-Driving Cars on California Roads

The carmaker’s autonomous vehicles traveled a total of 550 miles on California public roads in October and November 2016 and reported 182 “disengagements,” or episodes when a human driver needs to take control to avoid an accident or respond to technical problems, according to a filing with the California Department of Motor Vehicles. That’s 0.33 disengagements per autonomous mile. Tesla reported that there were “no emergencies, accidents or collisions.” Tesla’s report for 2015 specified that it didn’t have any disengagements to report.

Companies like Tesla with permits to test autonomous vehicles in the state are required to disclose the number of disengagements each year. The latest reports for 2016 — submitted by 11 companies including Daimler AG’s Mercedes-Benz, Alphabet Inc.’s Waymo and General Motors Co.’s Cruise — were made public Wednesday by the state’s DMV.

Auto industry analysts stress that the California reports are an imperfect metric, because most companies are testing their vehicles in other countries and states like Michigan, Arizona and Nevada, not to mention on private tracks.

Additionally, not all driving miles are created equal, and highway miles are far different than those racked up in tricky urban environments. BMW reported that it had just one disengagement in 638 miles driven, but specified in its report that the incident occurred on U.S. Highway 101 with dry roads and clear weather. Mercedez reported 336 disengagements in 673 miles, but said that all of its reported miles were on urban streets with no highway driving.

“It’s a snapshot and it’s directionally interesting, but it doesn’t tell you everything,” Mike Ramsey, an analyst at Gartner, said of the disengagement reports.

Ford Motor Co. reported that it tested a Fusion hybrid sedan in March and that it had three disengagements in 590 miles. Honda Motor Co. and Volkswagen AG both filed reports saying that they did not operate any autonomous vehicles in California during the period.

Waymo had a much lower rate of disengagements in 2016, improving to about 0.2 disengagements per thousand miles from 0.8 a year earlier. Chief Executive Officer John Krafcik first shared the data during a speech at the North American International Auto Show in Detroit last month.

Based on that metric, Tesla disclosed a rate of about 330 disengagements per thousand miles, although the company’s vehicles traveled fewer miles than Waymo’s on California public roads last year. “Tesla conducts testing in simulation, in laboratories, on test tracks and on public roads in various locations around the world,” said the company in its report to the California DMV.

This fall, Tesla announced that all cars being made at the company’s Fremont, California factory were shipping with new hardware that would enable full self driving. Tesla’s website features a 2-minute video about full autonomy. The company said it has also gathered more than 300 million miles of data from cars driven by customers with Autopilot engaged, giving it a treasure trove of real world data.