Among different road user types, drivers represent the largest share of road fatalities. As a result, more attention should be paid to the behavior of drivers, especially their behavior over time. By using driving simulator data, this study aims to investigate the relative performance of individual drivers over time. To this end, 20 participants (14 in the end) completed a particular simulator scenario over five days, and their driving performance at various points along the driving scenario was recorded. By taking all this information into account, the technique of data envelopment analysis was applied to assess the relative performance of each driver, and the window analysis was used to measure the variations in performance over time.