This paper describes partial automation of Wizard of Oz usability studies. Such simulations allow for interactive usability testing and user feedback on software or human-machine-interfaces prior to building a working prototype. We believe that the wizard needs tool support to be effective and have developed a tool called UsaWiz to help automate the interpretation of generic multimedia user input cues, and in quickly developing high level prototypes. In particular, this concept addresses one of the weaknesses of the major usability engineering techniques: the reproducibility of the study under the same conditions. The subjective influences of test conductors are limited to a minimum. Furthermore all test-data is streamed efficiently. The introduction of a usability experiment control language and a modular unit construction system are the heart of the generic nature of the concept. Besides the basic goals a realization of the presented ideas is introduced and evaluated regarding in particular performance and savings achieved by the approach. Especially for studies in the automotive environment an exemplary distraction task and baseline evaluation are also explained in detail.