Companies testing self-driving cars on California streets gave a peek into the inner workings of their real-world test drives last week. The big takeaway? Many are still a long way from letting drivers take their hands off the wheel.  Most manufacturers are developing self-driving technology in secret, using private test facilities and virtual simulations. The California Department of Motor Vehicles’ annual disengagement report, 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.  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.”  Waymo drove the highest number of miles in autonomous mode. The company said its 75 vehicles drove 352,544 miles in California, with 63 human takeovers — a rate of 0.18 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 0.79 disengagements per 1,000 miles driven.  Teslasaid it did not drive any autonomous miles on California roads in 2017 “as defined by California law.”  BMW, Ford Motor Co., Honda Motor Co., Chinese EV startup Nio and Volkswagen also reported driving zero autonomous miles.