Today, in automobile industry we have a lot of movements to get the competitiveness in cost, safety and quality aspect for the world market competition. System effectiveness in cost, safety, quality is now the target to be achieved. So, car manufacturers are faced today to improve the system quality of car, to reduce the total system cost and to control the functional complexity for safety and convenience in the system. To meet the requirement of car manufacturer for the complexity control and to give more safety and better quality and reliability, Siemens has developed several concepts in car body electronics. The main point of this concept is simultaneous system approach concept in order to get the whole system efficiency, including EDS concept for new architecture, integration of stand-alone units, concept of multiplexing for additional functions, and mechatronics approaches. Based on the simultaneous system approach concept, system analysis can be carried out, beginning with detail in functional aspect and grade of integration, in aspect of EDS, system safety and system cost savings. With these analysis results, manufacturing concept, testability and logistics can be optimized with car manufacturer strategy. For all functions/units which are involved in this system analysis, Siemens provides solutions with modular development concept.