Routing protocols for Mobile Ad hoc NETworks resort to broadcast in order to achieve their main functionalities such as node discovery, topology dissemination, route discovery and self-organizing. In order to reduce the impact of routing traffic and other broadcast traffic generated by the applications, clustering is one of the main approaches widely investigated. Recently, the Chain-Branch-Leaf (CBL) scheme has been proposed to exploit the spatial constraints of the road in order to achieve an efficient clustering in Vehicular Ad hoc NETworks routing protocols. In this paper, CBL is enhanced in order to improve the stability of the individual clusters and that of the resulting backbone by extending the duration of the connections between cluster nodes and their cluster head. The evaluations through simulation establish its performance in comparison with some protocols available in OPNET and that are representative of the different routing approaches in ad hoc networks, namely AODV for reactive, OLSR for proactive and GRP for geographic routing. The results show that CBL allows better performance at the Wireless LAN level, but also that it still has a potential for improvement in terms of quality of service.