###### Abstract
To solve these problems, the cluster vehicle method is mostly introduced in the current vehicle communication. This method treats a certain number of vehicles as a cluster, and performs vehicular communication and link management in units of clusters [18; 19; 20; 21; 22]. We noticed that [PERSON] et al. in [13] designed a routing mechanism named traffic differentiated clustering routing (TDCR), which integrates DSRC and C-V2X into a framework from the perspective of balancing QoS and communication costs. This routing mechanism has received much attention. However, we discovered that, to ensure the successful establishment of the communication link, TDCR uses a vehicle clustering method based on spatial sampling, and the sampling radius is too small, which leads to an excessive number of forwarding nodes in the routing path of TDCR. According to the routing method of TDCR, there is a certain probability that the routing path cannot be successfully established. As the amount of data increases, the performance of TDCR sharply deteriorates. Inspired by TDCR, we designed a new vehicle clustering method that does not rely on inter-vehicle negotiation and spatial sampling. Based on this clustering method, the number of hops in the communication link between vehicles and the roadside unit (RSU) in VANETs can be effectively reduced. Additionally, from the perspective of balancing QoS and communication costs, a hybrid routing method based on cluster and traffic differentiation was redesigned. This method is referred to as the cluster-based traffic differentiated hybrid routing (CTDHR). The contributions of this paper are presented as follows:  
* A vehicle clustering method based on the idea of hierarchical clustering is proposed. The clustering method--to ensure the stability of clusters--changes the conditions in the hierarchical clustering algorithm to measure whether two clusters can be merged, and also makes some modifications in other aspects to adapt the clustering method to the vehicle clustering scenario. The proposed clustering method not only ensuresthe stability of the cluster, but also reasonably controls the number of clusters, reduces the number of hops in the VANET link, and reduces the delay in transmitting the information. * From the perspective of balancing QoS and user communication costs, the vehicular communication in the CTDHR framework is modeled, and a heuristic algorithm is proposed to solve the model. In addition, the hybrid routing of DSRC and C-V2X based on this model is completed in the heuristic algorithm. * A simulation environment that is as close to reality as possible was designed and utilized to test the performance of CTDHR. The experimental results show that CTDHR has better performance than the existing DSRC and C-V2X hybrid frameworks. This paper is organized as follows: We review related research work in Section 2 and describe the CTDHR framework in detail in Section 3. In Section 4, the vehicle cluster model and hybrid routing model are presented. In Section 5, a heuristic algorithm based on the routing model is designed. In Section 6, the CTDHR performance is tested in a simulation environment that is as close to reality as possible. In Section 7, we summarize our research.