In-vehicle electronics is displacing the traditional mechanical interfaces and as a result, electrical architecture design is evolving and getting more complex due to increase in automotive electronic content. Several embedded communication protocols are used to build an electrical architecture, with predominant use of Controlled Area Network (CAN) and Local Interconnection Network (LIN). Demand for new electrical features is increasing, to meet and to exceed the customer expectations and also to adapt to new evolving electronic technologies. To accommodate future electrical content, the need for communication bandwidth is increasing at an exponential rate. In addition, some of the safety-critical features require predictability and deterministic network behavior. Current protocols are not capable of satisfying these demands. FlexRay protocol can address these needs with higher bandwidth and determinism. FlexRay protocol will most likely become the de-facto standard for next generation in-vehicle communication for safety critical subsystems. Early design validation of FlexRay protocol is needed before it is successfully used. FlexRay based communication architecture design for data communication has challenging aspects for the designer. In order to build a robust architecture, the system designer needs quantitative methods and tools to make the design decisionsThe design metrics listed in this paper are important in making the design decision by predicting the key aspects of the FlexRay protocol. Metrics such as utilization and message latency are discussed in detail with an example use case. It is also demonstrated how these metrics can be used for designing a robust architecture, with brief conclusion.