The increasing number of electronic control units (ECUs) in vehicles leads to more and more complex systems with a steadily growing demand for data exchange. This growth includes the number of bus participants, the amount of data and hence the data transfer rates. In addition, the trend towards car-to-x connectivity reinforces the need for new in-vehicle communication solutions.Since the early 1990s Controller Area Network (CAN) is the most widely used powertrain bus system. Since 2000 FlexRay is used in addition to CAN in the premium segment. For classic powertrain applications, the data transfer rates of these bus systems are sufficient; however the utilization is sometimes difficult and gateways are often required. For new applications like hybrid and electric vehicles and the next generation of external communication applications (e.g. telematics services) new concepts based on the existing bus systems or completely new solutions are needed. Looking outside of automotive business, Internet Protocol over Ethernet (IPoE) is the current standard technology for consumer and industry applications. IPoE has, compared to the currently used systems in powertrain area, very high data transfer rates and has the potential for further system cost reduction using standardized solutions. A first automotive application of IPoE was introduced in the market in 2008 for external communication. So far, IPoE is expensive compared to CAN and FlexRay due to higher hardware costs. Since a new transceiver technology enables the introduction of Ethernet in vehicles and Ethernet communication controller integrated into the microcontroller will be available for future powertrain ECUs, both evolutions together can be the enabler for Ethernet sub-bus systems in vehicles. Major technical challenges for the introduction of Ethernet in powertrain are the achievement of the necessary robustness under automotive conditions (electromagnetic compatibility (EMC), temperature range, mechanical vibrations) and the fulfillment of automotive real time, security and safety requirements. In addition, the capability of fast and easy adaptation to different vehicle configurations is mandatory. At the same time, the cooperation between original equipment manufacturer (OEM) and supplier needs to be considered to ensure an efficient integration and development.This paper analyses applications and the communication extend in current powertrain systems. A forecast for the future demand of communication capacity is calculated. Based on this, requirements are extracted and applied to Ethernet as well as IPoE. The result is an uncompromising approach to migrate in-vehicle powertrain communication to Ethernet and IPoE. Technical and process related requirements are considered to obtain a coherent picture.