High-quality delivery of compressed video over vehicular networks is a very challenging task. In this paper, we propose a cross-layer mechanism dedicated to high-efficiency video coding (HEVC) low delay temporal prediction structure in order to improve the video transmission through vehicular ad-hoc networks (VANETs). Compressed video is obtained thanks to the state-of-the-art HEVC video coder which exploits new efficient coding tools and structures. Then, a mechanism is proposed which accounts for the type of each frame as well as the network traffic load state. Furthermore, the proposed mechanism guarantees better resources exploitation of the VANET oriented IEEE 802.11p standard. Indeed, the proposed system exploits the medium access control (MAC) layer access categories (ACs) that are not dedicated to video transmission. The results obtained from realistic VANET simulations demonstrate that the proposed cross-layer mechanism achieves significant improvements compared to the actual standard in terms of packet delivery rate as well as PSNR gains at the reception