Renewable energy and electric vehicles (EVs) are two key developments of smart grid. To support the increasing charging demands of EVs, more charging stations need to be constructed. Some charging stations are located in remote areas and they mainly rely on renewable generations for energy provisioning. Due to dissimilar self-generations and local energy demands at different locations, it is beneficial to share the energy among themselves for a sustainable eco-system. Powered by the smart city vision that revolutionizes the energy and transportation sectors, vehicular energy network (VEN) is developed, which can distribute energy across a geographical area by means of EVs. In this paper, we formulate an optimization problem to optimally coordinate energy exchange among renewable-enabled or off-grid charging stations based on VEN. We also propose a heuristic to develop some high-quality energy tracks for energy exchange, which can significantly reduce the computational time. We evaluate the energy exchange performance on some random networks of various sizes. Simulation results demonstrate that the proposed design can effectively deliver excessive energy over VEN and the proposed heuristic can drastically reduce the computational time without significantly undermining the performance.