Why disable the autopilot?

The number of systems in commercially available vehicles that assist or automate driving tasks is rapidly increasing. At least for the next decade, using such systems remains up to the discretion of the user. In this paper, different reasons why drivers may disengage the autopilot are investigated. This was done through a simulator study in which the system could drive fully automated, but where participants could also disengage the system. Qualitative data were collected about why participants disengaged the autopilot. The analysis of the data revealed six themes covering the reasons why participants disabled the autopilot: The speed maintained by the autopilot, the behavior of the autopilot in relation to overtaking other vehicles, onset of boredom, onset of sleepiness, lack of trust in the autopilot, and enjoyment of manual driving. On the basis of the results, design opportunities are proposed to counteract the tendency to not use automated driving systems.