Various convenient systems which are telecommunication and navigation system and safety system which include Antilock Braking System, Electronic Stability Control, Adaptive Cruise Control have been developed and applied to meet customer needs and each standards since vehicles are used. The complexity of new electronics become significant reason of breakdown especially embedded software failures. Hardware reliability is almost stabilized with long history but software reliability needs more improvements through reliability researches. This new challenge will improve software reliability to clear its overall failures in vehicles. This paper introduces some software reliability models and evaluates embedded software reliability using failure data which occurred during operating.