The objective of this paper was twofold: firstly, we wanted to examine whether the original Driving Anger Scale (DAS) and the original Driving Anger Expression Inventory (DAX) apply to German professional taxi drivers as these scales have previously been given to professional and particularly to non-professional drivers in different countries. Secondly, we wanted to examine possible differences in driving anger experience and expression between professional German taxi drivers and non-professional German drivers.

We applied German versions of the Driving Anger Scale (DAS), the Driving Anger Expression Inventory (DAX), and the State-Trait Anger Expression Inventory (STAXI) to a sample of 138 professional German taxi drivers. We then compared their ratings to the ratings of a sample of 1136 non-professional German drivers (Oehl and Brandenburg submitted).

Regarding our first objective, confirmatory factor analysis shows that the model fit of the DAS is better for non-professional than for professional drivers. The DAX applies neither to professional nor to non-professional German drivers properly. Consequently, we suggest modified shorter versions of both scales for professional drivers. The STAXI applies to both professional and non-professional drivers. With respect to our second objective, we show that professional drivers experience significantly less driving anger than non-professional drivers, but they express more driving anger.

We conclude that the STAXI can be applied to professional German taxi drivers. In contrast, for the DAS and the DAX we found particular shorter versions for professional taxi drivers. Especially for the DAX most statements were too strong for German drivers to agree to. They do not show behaviors related to driving anger expression as they are described in the DAX. These problems with the original American DAX items are in line with several other studies in different countries. Future investigations should examine whether (professional) drivers from further countries express their anger as proposed by the DAX. In addition, professional drivers experience less driving anger (DAS) and less general trait anger (STAXI) than non-professional drivers, but they report more driving anger expression (DAX) and more current general state anger (STAXI). Subsequent studies should therefore focus on different types of anger within the group of professional drivers.