Google has revealed that in the last 14 months, its autonomous cars almost crashed 13 times.
49 of the company's autonomous cars were tested on 424,331 miles of California road during those 14 months.
The information follows a request from the Department of Motor Vehicles which requires companies to provide 'disengagement reports'.
A computer simulation run after the tests indicated that 13 incidents where drivers were forced to take control would have resulted in a crash..
Two cases would have involved hitting a traffic cone while the others would have been more serious.
Further information revealed 272 cases in which the cars automatically handed control to the driver due to a detected technology failure.
There were also 69 times where drivers chose to take control for 'reasons relating to the comfort of the ride, safety of the vehicle, or the erratic or unpredictable behaviour of other road users'.
Related: Android Auto review
Google was not the only company to disclose information relating to its self-drive car project.
Six other companies also revealed data about autonomous vehicle disengagement, including Nissan, Mercedes, and Tesla.
Google is aiming to create fully autonomous cars without manual controls, but is facing pressure from regulators and watchdogs.
In its disengagement report, the company says that driver interventions 'are rare and our engineers carefully study these simulated contacts and refine the software to ensure the self-driving car performs safely.'
Recently Google and Ford were reported to be teaming up on a self-driving car project, although an expected official announcement at CES 2016 never came.
Do think these are just teething issues or seriously bad signs for the future? Let us know in the comments below