SAN FRANCISCO -- Companies testing self-driving cars on California streets gave a peek into the inner workings of their real-world test drives on Wednesday. The big takeaway? Many are still a long way from letting drivers take their hands off the wheel.
Most manufacturers are still developing self-driving technology in secret, using private test facilities and virtual simulations, so there is little data publicly available to track their progress. The California Department of Motor Vehicles' annual disengagement report released Wednesday, though not comprehensive, provides a snapshot into how far along these companies may be.
Nineteen of the 50 companies -- up from nine in 2017 -- registered to test vehicles on public roads in California and reported the number of times a safety driver had to regain control of the vehicle in the past year. Companies are only required to report disengagements if they've been permitted for the full year.
The DMV defines a disengagement as "a deactivation of the autonomous mode when a failure of the autonomous technology is detected or when the safe operation of the vehicle requires that the autonomous vehicle test driver disengage the autonomous mode and take immediate manual control of the vehicle."
Such parameters have been widely interpreted by manufacturers. For example, Nissan wrote in its report that it does not count disengagements to start or finish a test run, while chipmaker Nvidia wrote that it does.
Permitted companies are also required to report crashes to the agency, though those are filed separately at the time of the accident.
Waymo, Google's self-driving car affiliate, by far drove the highest number of miles in autonomous mode, though it has been shifting some of its vehicles to other states such as Arizona and Michigan. The company said its fleet of 75 vehicles drove 352,544 miles in California, with 63 human takeovers -- a rate of .178 disengagements per 1,000 miles driven.
Cruise, General Motors' autonomous vehicle subsidiary, said it drove more than 125,000 autonomous miles among 96 vehicles, with 105 disengagements. That's a rate of .79 disengagements per 1,000 miles driven. Cruise had four days in October when it had four crashes in five days, according to accident data maintained by California.
Tesla said it did not drive any autonomous miles on California roads in 2017 "as defined by California law," rather using test tracks, laboratories and customer-owned vehicles that have autonomous technology operating in "shadow mode" to collect data.
BMW, Ford Motor Co., Honda Motor Co., Chinese EV startup Nio and Volkswagen also reported driving zero autonomous miles during the year.
Some reports included location of testing, cause of disengagement and the time required to take over control. Cruise and self-driving startup Zoox emphasized in their reports that their tests took place on urban streets in San Francisco. Companies such as Waymo, Zoox and autonomous vehicle startup Drive.ai frequently listed unwanted maneuvers or planning discrepancies as reasons for disengagements.