In the recent years, we are witnessing a growing interest into the design of smart vehicles and smart roads for Intelligent transportation systems. Vehicles as part of the Internet of Things should provide to the driver and passenger with a variety of services using efficient gateway discovery mechanism while maintaining a certain level of security and authentication to avoid potential malicious attacks. In this paper, we propose a secure hybrid adaptive gateway discovery and communication protocol for smart vehicular networks, which we refer to as SEGAL. Our proposed SEGAL protocol is based upon building a secure clustered vehicular network, and permits the exchange of gateway discovery messages through authenticated clusterheads and cluster members. We shall present the design of our protocol, and describe how it can overcome the possible malicious attacks that might harm the network. Then, we report its efficiency and scalability using an extensive set of simulation experiments using Ns‐2 simulator. Our results indicate that the proposed SEGAL protocol is scalable while achieving high success rate, low response time and dropping rate. Copyright © 2016 John Wiley & Sons, Ltd.