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In vehicular ad hoc networks (VANETs), the IEEE 802.11p is a popular and standardized protocol for communications among vehicles and infrastructure (e.g., roadside units). However, because of a limited communication range and the randomly access nature of the carrier sense multiple access with collision avoidance (CSMA/CA) mechanism, the end-to-end delay could be high due to both store-and-catch-up (SAC) delay when the network is temporally disconnected and the channel access contention delay. In this paper, we propose a new method based on fifth-generation device-to-device (D2D) technology to improve the delay performance of VANETs. The basic idea is that direct D2D-based communications among vehicles remove the contention delay and can support longer distance. Specifically, we design a hybrid system with both D2D- and IEEE 802.11p-based communications, where the D2D links are …