Controller Area Network has been widely used as an embedded field bus in real-time industry systems, in particular, for automotive digital communications. However, with the increasing criticality of automotive control systems (e.g. advanced driver assistance systems), automotive communication systems are required to support more dependable and flexible communication services. Upcoming car series will be deployed with flexible time-triggered communication protocols due to benefits with respect to bandwidth, predictability, dependability and flexible system integration. In order to support the reuse of existing CAN-based applications, flexible time-triggered CAN (FTTCAN) has been released to support more dependable and flexible scheduling real-time both periodic and sporadic messages by planning-based services. This paper exploits planning-based services of FTTCAN and proposes further a mixed planning-based scheduling (MPS) policy and its performance analysis. Through a case study of typical automotive communication, its performance is evaluated to support dependable and flexible requirements for automotive digital communications.