New reports required by the California Department of Motor Vehicles (DMV) from companies testing robot cars on the state's public roads show test drivers still had to step in often to maintain safety.

Waymo, formerly Google's autonomous vehicle unit, logged 352,544 autonomous miles in the state with its 75 robot cars. It reported a test driver took control 63 times, or once every 5,506 miles. The failure rate is slightly worse than the 2016 period when Waymo's robot cars drove 635,868 miles on California's roads and reported 124 disengagements, or one every 5,127 miles.

GM's Cruise division which claims it will put robot cars on the road in 2019 logged the second most miles of the 19 companies that were required to report on their testing. It drove 86 cars, a total of 131,675 miles and had 105 disengagements or one every 1,254 miles.

Another indication of the safety of the autonomous technology is the number of crashes involving the robot cars. Crashes must be reported to the DMV and the reports are posted on the DMV's website. GM Cruise has already reported two crashes this year. It had 22 collisions in 2017 and has logged a total of 25 since it began testing.

Google/Waymo had 3 crashes in 2017. It posted 13 in 2016 and 9 in 2015. It also has reported a total of 25 crashes since crash reports were required in 2014.

GM Cruise reported it is doing its testing in San Francisco because of the challenges it poses with traffic, pedestrians and cyclists "We drive here because by doing so we get better faster," the company said.

While 50 companies are licensed to test autonomous vehicles in California, only 19 companies were required to file disengagement reports covering 2017. Only those who received testing permits before Jan. 1, 2017 had to file reports covering last year. The others would first file 2018 reports, including their data for a portion of 2017 by Jan. 1, 2019.

Here are the 17 companies in addition to Waymo/Google and GM Cruise that were required to file "disengagement report":

• Baidu USA - Tested four vehicles, logged 1,971 miles and had 48 disengagements.
• BMW -- Didn't test on public roads.
• Bosch - Tested three cars, logged 1,454 miles and had 598 disengagements.
• Delphi - Tested one vehicle, logged 1,810.55 and had 81 disengagements
• Drive.ai - Tested seven vehicles, logged 6,572 miles and had 151 disengagements.
• Ford - Didn't test on public roads.
• Honda - Didn't test on public roads
• Mercedes Benz - Tested three vehicles, logged 1,087 miles and had 842 disengagements.
• NIO USA - Did not test autonomous vehicles on public roads.
• Nissan - Tested five vehicles, logged 5007 miles and had 24 disengagements.
• NVIDIA - Tested two vehicles, logged 505 miles and had 105 disengagements.
• Telenav - Tested one vehicle, logged 1,697 miles and had 58 disengagements.
• Tesla Motors - Reported it did not test autonomous vehicles on California public roads.
• Valeo North America - Tested one vehicle, logged 574 miles and had 215 disengagements.
• Volkswagen Group of America - Did not test on public roads
• Wheego - Did not test on public roads
• Zoox, Inc. - Tested 11 vehicles, logged 2,191 miles and had 14 disengagements.

You can view the 2017 disengagement reports here.