Product development is one of the core business processes for car manufacturers. Today it is heavily support by information systems enabling computer-aided technologies for design (CAD), engineering (CAE), and testing (CAT), which we refer to as CAx systems. In order to improve the alignment between business and IT we have created an enterprise architecture for the research and development department at AUDI AG. The description of the various relevant architecture domains is thereby based on ontologies. A web-based tool enables collaborative editing of these contents as well as complex analysis on various aspects relevant to IT management.