In 1991 the first premium passenger cars with CAN data bus technology in powertrain electronics came to market. Development of in-vehicle network concepts for comfort and convenience electronics on the basis of a standardized CAN protocol started in the same year.As a result, in-vehicle data bus technology is now in series production since early 1995 with four nodes in a 40 Kbps network which will be upgraded to more than 10 participants for MY 98 vehicles. Car manufacturer's design goals of wiring harness reduction (20 %) and cost reduction (10 %) have been fulfilled. In addition, new features like anti-theft and immobilization easily can be implemented by use of data-bus technology in combination with a gateway between class B an class C networks.Finally, the paper will describe the limits of today's network topology on the basis of current chip technology. System chip design and sensor/actuator integration will be a need to overcome today's net-work limitations.