The product development process within the automotive industry is subject to changing and varying demands due to external influences and internal strategic decisions. Influences and decisions, such as a shift from hybrid vehicles to fully electric architectures, turn into explicit requirements. For a manufacturer to remain competitive, these requirements need to be fulfilled within the early design phases of the development process. The car body substructure and body shop in particular have the highest interdependence with the automotive product development process. To reduce the resulting complexity of managing various requirements for each car body type, car manufacturers use modular design to create partitioned subassemblies. Although there is a wide range of strategies for the modularization of individual requirements, none of them offers the possibility of considering multiple influences and identifying interdependencies between formed modules. To solve this problem, we provide a structured approach for the early planning and design phases as means of achieving this multi-criteria modularization. We transform results from the requirement elicitation into dependency matrices to weight, compare and synchronize critical and relevant requirements. Thus, it is possible to analyze interdependencies to gain knowledge for the design of new product and production modules. In cooperation with the Mercedes-Benz Cars division, we validate our approach and create a domain-specific blueprint for car body substructures. Therefore, we are able to deepen the understanding, give part-specific recommendations and provide a new decomposition of modules of future vehicle architectures.