Impact factor as efficiency or sustainability are entirely correlated to the continuous development of the smart city concept technology application. Intelligent transportation systems (ITS) and particularly autonomous vehicles are expected to play an important role in this challenging environment. Fast and secure connections will be pivotal in order to achieve this new vehicular communications’ application era. The use of millimeter-wave (mmWave) frequency range is the most promising approach to allow these real-time high-demand applications which requires higher bandwidth with the minimum possible latency. However, an in-depth mmWave's channel characterization of the environment is required for a proper mmWave based solution deployment. In this work, a complete radio wave propagation channel characterization for a mmWave V2X smart parking solution deployment in a complex outdoor environment has been assessed, at 28 GHz frequency band. The considered scenario is a parking lot placed in an open free university campus area surrounded by inhomogeneous vegetation. Vehicle and vegetation density within the scenario, in terms of inherent transceivers density and communication impairments, leads to overall system operation challenges, given by multiple communication links operation at LOS and NLOS conditions. By means of an in-house developed 3D ray launching (3D-RL) algorithm, the impact of variable vehicle and vegetation density are addressed, providing coverage/capacity analysis and precise modelling estimations of small-scale and large-scale multipath propagation effects in terms of received power levels and time domain characteristics. The obtained results along with the proposed simulation methodology, can aid in an adequate characterization of the mmWave communication channel for new vehicular communications networks, applications and deployments, considering outdoor conditions as well as the impact of different vehicles and vegetation densities, for current as well as for future wireless technologies.