Tesla started testing four self-driving cars on California’s public roads late last year, a milestone for CEO Elon Musk who has promised to demonstrate an autonomous road trip from Los Angeles to New York by the end of 2017, according to Bloomberg.

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 Mercedes-Benz, Waymo and Cruise, were made public 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. This fall, Tesla announced that all cars being made at the company’s 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.