5G enabled Vehicular ad hoc network (5G-VANET) plays a promising role to support diverse intelligent transportation system (ITS) applications. There are three types of communication modes in 5G-VANET: cellular mode, reuse mode and dedicated mode, i.e., vehicle users (VUEs) communicate with each other using the cellular network spectrum directly, in an underlay sharing way, and utilizing the allocated dedicated spectrum, respectively. However, how to dynamically share the multi-mode spectrum to optimize the network performance (i.e., network throughput) in 5G-VANET is a challenging task due to the high dynamic VANET environment and network resource heterogeneity. In this paper, we propose a dynamic Stackelberg pricing game enabled multi-mode spectrum sharing solution in 5G-VANET. In specific, we develop an access price strategy for different spectrum sharing modes considering the cellular BS's revenue and whole network throughput, while VUEs can select communication modes in a distributed way and dynamically change the selections through an evolutionary game. Through testing different traffic scenarios generated by SUMO, we demonstrate the effectiveness of the proposed algorithm. Specifically, the proposed algorithm can improve the total transmission rate of VANET by at least 20% compared with the random selection method.