Implementation of real time critical, QoS on-demand, bandwidth 'hungry applications over high speed dynamic vehicles, demand major research works to be carried out. Task of providing the optimal QoS over a specific period of time has been suggested as a challengeable problem in current VANET research groups. This paper discusses on the importance of providing QoS using variable metrics such as speed, radio propagation range etc. Study analyzes the support of standard adhoc routing protocols such as GPSR, DYMO over VANET, which shows best effort QoS utilization in response to demand on bandwidth in use over an established session for different type of services. This paper has discussed on vehicular parameters such as Vehicle Priority, Service Priority in order to improve QoS over a session consistently. Simulation test runs are generated using ns2[l] over a highway scenario map (support of VanefMobisim [2]), in order to ascertain the QoS efficiency over VANET. © IDOSI Publications, 2011.