Intelligent Transportation Systems (ITS) improve passenger/pedestrian safety and transportation productivity through the use of vehicle-to-vehicle and vehicle-to-roadside wireless communication technologies. Communication protocols in these environments must meet strict delay requirements due to the high moving speed of the vehicles. In this paper, we propose an energy-conservative MAC layer protocol, named DSRC-AA, based on IEEE 802.11 that provides power saving to the ITS communication modules (e.g., On Board Units, portable devices, and Road Side Units) while ensuring the bounded delay. DSRC-AA, a generalization of the Asynchronous Quorum-based Power-Saving (AQPS) protocols, capitalizes on the clustering nature of moving vehicles and assigns different wake-up/sleep schedules to the clusterhead and the members of a cluster. DSRC-AA is able to dynamically adapt the schedules to meet the communication delay requirements at various vehicle moving speed. Simulation results show that DSRC-AA is able to yield more than 44 percent reduction in average energy consumption as compared with the existing AQPS protocols, if to be used in vehicular networks.