Information exchange is not easily secured in the emergency cases where the normal telecommunication infrastructure might have been collapsed. When vehicles are moving on a highway, communications between the vehicles and the base stations always result in a high delay that causes a vehicle to fail to verify all the messages received from the neighbors in real time. These situations may result in message losses and even security risks. To address these issues, we propose a scheme that combines the technologies of trusted network connect and multi-secret sharing to securing authentication and verification for ad hoc vehicles (SAV4AV), in which a new vehicle is permitted to flexibly join in a platoon through collaborating with t existing vehicles and thereby to accomplish identity authentication and integrity verification. We list several possible attacks and provide a detailed security analysis on how to avoid these threats in SAV4AV. Moreover, we perform extensive simulations to investigate the performance of SAV4AV against various network scenarios with respect to time consumption and network throughput. Copyright © 2014 John Wiley & Sons, Ltd.