Today, electronics are an indispensable part of modern vehicles. Cars of moderate class contain more than 70 electronic control units connected by different data buses and gateways. The communication protocols are characterized in event-triggered and time-triggered mechanism. Several event-triggered protocols LIN, CAN, J1850, etc. and TTP, SPIDER, Byte flight, Lon Works, Flexray, etc. are the time-triggered protocol have been in the market. In this paper the most highly preferred protocol CAN is compared with the newest Flexray. CAN has a good performance in terms of bandwidth utilization, but is not considered deterministic enough to be used in safety critical applications which require high reliability and dependability. TTP being developed with extensive research for highly dependable systems i.e., hard real-time systems but is inefficient in terms of network utilization and lacks in flexibility. Flexray is a hybrid protocol taking advantages of both event-triggered and time-triggered approaches providing dynamic and static communication depending on the severity of link usage in the network. The advantages and constraints of the protocols in the network designer’s perspective are described.