Recent years have seen a growing interest in Vehicular Ad hoc Networks (VANETs) and their benefits to the development of intelligent transportation systems (ITS). With the deployment of multimedia services over VANETs, there is a need to develop new approaches to insure higher level of quality of services (QoS) for real time applications, and integrate QoS into routing protocols. However, in VANET environment, it is not an easy task to search for routes which satisfy the QoS required by the applications. In this paper, we propose CBQoS-Vanet, a new QoS-based unicast routing protocol for vehicular networks. This protocol is based on the use of two techniques: A clustering algorithm which organizes and optimizes the exchange of the routing information based on QoS requirements, and an artificial bee colony algorithm, which finds the best routes from a source to a destination based on QoS criteria. In our approach clusters are formed around cluster-heads that are elected based on QoS consideration. In this paper we consider the following QoS criteria: Available bandwidth, end-To-end delay, jitter, and link expiration time. Through simulation experiments, we show that our method can improve greatly the performance of routing in VANET by selecting routes based on the above mentioned QoS criteria.