In this paper, we investigate a multicast routing problem with quality of service constraints on ad hoc vehicular networks. An integer programming formulation for the problem is proposed that forms the basis of a relax-and-fix heuristic designed with the goal of producing feasible solutions of good quality. In addition, preprocessing procedures relying on simple and constrained shortest paths are developed that reduce the model size to the point of making it viable to compute. Computational experiments on benchmark instances generated to mimic realistic settings are reported. The results highlight the effectiveness of the relax-and-fix heuristic and the importance of the preprocessing routines for the computability of the proposed mathematical model. the most important intelligent transport systems are ad hoc vehicular networks or VANETs (Bitam and Mellouk, 2013). A VANET is a type of MANET where nodes are vehicles. There are two types of communication in VANETs: between vehicles (V2V-vehicle to vehicle) and between vehicles and infrastructured nodes (V2I-vehicle to infrastructure), also called RSU (roadside unit). Karim (2008) showed that VANETs are more suitable for vehicular communication because they have lower costs of implementation and communication even in places where there is no infrastructure. In addition, VANETs also have lower latency in data delivery when compared to other technologies such as 3G/4G networks and infostations.One possible application of VANETs consists in assisting vehicles to communicate and coordinate with each other, with the aim of avoiding any type of critical situation such as road accidents, traffic jams, and poor roads, as well as other applications such as speed control, detailed information on accidents for rescue teams, free passage of vehicles, and invisible obstacles. Another category of applications is information and entertainment for passengers and drivers. These are called applications for the comfort of drivers and passengers, such as Internet access, chats and interactive games between cars next to each other, free places for parking, and detailed information on fuel price, among others.In view of their high node mobility, the protocols of routing in vehicular ad hoc networks must be properly adapted and offer optimized routing. According to Peterson and Davie (2012), in a communication network there are three fundamental methods for data transmission: unicast, broadcast, and multicast. The multicast routing strategy reduces the communication cost and strongly explores the bandwidth and network resources, since the data packets can be transmitted to all destinations (members of the multicast group) by a single transmission, while with the unicast routing the source node sequentially transmits the same packet several times to different destinations and with the broadcast routing the source node transmits to all nodes in the network, whether they are interested or not in the message.In a VANET, as well as in other types of networks, many applications have special req...