Optimized over a period of years, today's car body assembly systems enable to produce two, sometimes three and theoretically even up to four different variations of car bodies on one single production line. This is typical for high volume production using highly automated systems. Trying to satisfy customer needs towards more and more individuality even concerning the aspect of car body design and features, manufacturers are forced to increase the diversity in car body structures and provide to the market a high number of derivates in addition to their main product lines. Having in mind the high investment, needed for high productive, high reliable assembly systems, the aspect of flexibility and changeability in production program, realized by new structures enabled and provided especially by more flexible production equipment has to reach a general new level of improvement. This aim will not only be achieved by organizational solutions; rather the total technical approach and interaction of equipment components have to be analyzed and adopted to this task. The authors of this paper have been involved in several analysis and case studies concerning this topic, mainly in close link with automotive OEM's and suppliers. As a result, a whole system of different approaches for flexibility with a specific focus on the positioning, clamping and fixture systems for typical joining processes in body in white production units has been developed, partly tested. Additionally these technical solutions have been completed by methods to design and dimension those systems. Major concern was given to the economical aspect, by this trying to avoid the usual conflict between flexibility and higher costs Even aspects of energy and resource efficiency were implemented into all these considerations. Beside an overview of the industrial application the paper will base on and provide with results, achieved on an experimental car body research test unit and its components that were developed and are now used and tested in the laboratories of the Fraunhofer Institute IWU in Chemnitz.