This paper presents a qualitative study of FlexRay and Ethernet in in-vehicle communication networks. Although both protocols have experienced fast growth in the past years, they still have some important deficiencies that deserve attention. This qualitative study has not only outlined the important shortcomings of in-vehicle FlexRay and Ethernet, but also identified their unique competitive edges, respectively. Intensive analyses of both protocols are carried out from three key perspectives: system cost, data transmission capacity and fault detection capability. Some improving approaches have also been pointed out. It is revealed that at the current stage FlexRay is better than Ethernet in transmitting time critical signals deterministically, but has higher cost and complexity. Ethernet, though less deterministic than FlexRay, possesses much greater bandwidth and can transmit data at quite small latency and jitter. This qualitative study has indicated that both protocols need further improvement to meet the requirements of future in-vehicle networks, yet Ethernet may lead the development and expand faster.