An important question in automated driving research is how quickly drivers take over control of the vehicle in response to a critical event or a takeover request. Although a large number of studies have been performed, results vary strongly. In this study, we investigated mean takeover times from 129 studies with SAE level 2 automation or higher. We used three complementary approaches: (1) a within-study analysis, in which differences in mean takeover time were assessed for pairs of experimental conditions, (2) a between-study analysis, in which correlations between experimental conditions and mean takeover times were assessed, and (3) a linear mixed-effects model combining betweenstudy and within-study effects. The three methods showed that a shorter mean takeover time is associated with a higher urgency of the situation, not using a handheld device, not performing a visual non-driving task, having experienced another takeover scenario before in the experiment, and receiving an auditory or vibrotactile takeover request as compared to a visual-only or no takeover request. A consistent effect of age was not observed. We also found the mean and standard deviation of the takeover time were highly correlated, indicating that the mean is predictive of variability. Our findings point to directions for new research, in particular concerning the distinction between drivers' ability and motivation to take over, and the roles of urgency and prior experience.