The German Driving License Ordinance (Fahrerlaubnis-Verordnung; FeV) specifies five dimensions of mental performance as integral parts of the overarching construct of fitness to drive: resilience, orientation, concentration, attention, and reactions. However, a clear definitional distinction between these five dimensions of mental performance does not appear to be possible without further ado. Based on previous research in this field, factory analyses were conducted in this study using data from the Vienna Test System (WTS) of 5757 traffic psychological examinations from Austria. Due to a lack of data on the orientation dimension, only the remaining four dimensions could be included in the analyses. The results of the factor analyses do not reflect the expected factorial structure even after taking into account various result variables of the test procedures. The relationship between the empirically determined factors and the legally defined dimensions will be discussed critically. Taking into account the present results, the question of what the test procedures used in this study actually measure should be investigated further in the future.