Reliability and stability for connectivity are the important factors to enhance inter-vehicular communication. In order to achieve such factors, challenges especially in a large city environment due to signal attenuation and a typically poor transmission coverage issues are investigated. Both issues are caused by the existence of obstacles (i.e., overpass constructions and buildings) and road level topology (i.e., a three-dimensional case). Thus, this paper investigates explicitly the horizontal and vertical transmission distances that apply in a three-dimensional case. These distances are covered by existing propagation models of a large city by modeling them as a log-distance path loss with obstacle fading. The scenario of the dedicated three-dimensional case is simulated through the introduction of Vertical Relative Angles (VRA) and Horizontal Relative Angles (HRA) as supporting factors for the forwarding decision. The evaluation shows that applying HRA and VRA reach higher delivery ratio and reduces relatively lower delay in a large city scenario.