Software-defined networking (SDN) is considered as one of the main enabler technology of 5G that is expected to propel the penetration of vehicular networks. The rapid development of wireless technology has generated an avalanche demand for bandwidth-intensive applications (e.g., video-on-demand, streaming video, etc.) causing an exponential increase in mobile data traffic. Moreover, the use of edge caching technique enhances network resource utilization and reduce backhaul traffic. Many incentive mechanisms have been developed to encourage caching actors to enhance the caching process. In this paper, we propose an SDN based incentive caching mechanism for a 5G-enabled vehicular network. Our caching strategy consists of a small base station (SBS) that encourages mobile vehicles equipped with embarked caches to store and share its popular contents using vehicle to vehicle (V2V) communication. SBS aims to offload the cellular core links and reduce traffic congestion, where cache-enabled vehicles compete to earn more SBS reward. The interaction between the SBS and the cache-enabled vehicles is formulated using a Stackelberg game with a non-cooperative sub-game to model the conflict between cache-enabled vehicles. The SBS acts first as a leader by announcing the number of popular contents that it wants to cache and the cache-enabled vehicles respond after by the optimal number of contents they accept to cache and the corresponding caching price. Two optimization problems are investigated and the Stackelberg equilibrium is derived. The simulation results demonstrated the efficiency of our game theoretical based incentive V2V caching strategy.