In IEEE 802.11p based vehicle-to-infrastructure networks, there exists an access unfairness problem which results due to the existence of multi-velocity vehicles in the network. A high speed vehicle has less opportunity to communicate with the road side unit (RSU), when competed with a low speed vehicle, owing to their reduced time in which the vehicle resides within the scope of RSU. Accordingly, the data transferred by high speed vehicle is in reduced amount as compared to that of vehicle with lower speed. In this paper, we focus on resolving the unfairness problem by altering the transmission opportunity (TXOP) limit of vehicles in accordance to their average velocities. Further, to improve the aggregate data transferred, a novel scheme called block Acknowledgement (BA) scheme is introduced in V2I networks. BA scheme reduces the overhead of ACK transmission by integrating multiple ACKs of data frames in a TXOP limit into a block ACK frame. Considering a single-rate, multi-lane, V2I network, we prove that, fairness (equal chance of communicating with RSU) can be attained; simultaneously, aggregate data transferred can be improved when BA scheme is implemented along with TXOP differentiation. Analytical results are provided and validated using simulation studies. Unfairness, Fairness, IEEE 802.11p, TXOP differentiation, Block ACK, V2I Networks