Due to the vehicle's movement and inherent characteristics of wireless channel, how to discover and retrieve the required contents has become a challenging issue in a hybrid network including vehicular ad hoc networks (VANETs) and the Internet. In this paper, we propose a social cluster-based P2P framework that estimates similarity and connection condition among peers to provide mobile peers efficient resource discoveryand retrieval. The idea of our framework is to consider a mobile peer's preference and its connectivity such as the lifetime or the bandwidth for a wireless link. Specifically, there are two major components in our framework. First, a social cluster-based overlay structure and lifetime-aware flooding scheme enable mobile peers to discover resource through the Internet and VANETs. Second, a connectivity-aware retrieval scheme considers connection lifetime and bandwidth schedules and determines how to retrieve resource from available peers. The simulation results show that, compared with other existing P2P schemes, our social cluster-based P2P framework is able to quickly locate more available peers holding the required contents and achieve a higher retrieval ratio.