Software is becoming more and more important to the automotive industry as a driver for innovation, thus the number of software-based systems in the automobile value creation constantly rises. Because of this trend, automakers increasingly focus on the development of end-user oriented functions. In order to be able to successfully offer such functions, the requirements of customers for those applications have to be met. The automotive sector, still oriented at developing the product “car” and organized in a strict hierarchy, lacks the means necessary to systematically elicit and analyze the customer requirements thus far. This article shows how a prototyping tool can contribute to the active integration of the customer into the development process during participatory design of applications. One central aspect of the prototyping tool presented here is that the prototypes using it can be integrated into the car and used along with applications that are already in series production. It is hence possible to conduct pilot studies of the application with representatives of its target customer group in the future environment. This enabling of customers to experience the future application allows car manufacturers to systematically elicit and analyze their users’ needs. It also allows the collection and evaluation of innovative ideas by customers for new applications, as well as solutions for existing problems, for later integration into the companies’ products.