SDN's ability to provide a global view, centralized control, and flexibility in orchestrating network infrastructure are expected to overcome challenges in the dynamic conditions of vehicular communications. We are looking to rely on SDN technologies to achieve Vehicular communications capacity and performance, which increase the safety of vehicles and transportation, save cost & energy, and increase the vehicles' autonomy level. The usage of SDN in vehicular communications has been the subject of considerable research. Researchers address challenges such as low latency, high throughput, reliability, dense VANET, security, and scalability. Furthermore, this paper surveys the integration of SDN and other enabling technologies with vehicular communications, both for IEEE 802.11 and the C-V2X RAT families. It begins by discussing performance comparisons and coexistence between IEEE 802.11 and C-V2X standards, implementation of SDN in various use cases, integration of SDN with other enabling technologies, the study of particular SDN components to support vehicular communications performance, and SDN usage to support the specific issues vehicular communications. Finally, open directions and challenges of the research are discussed.