This book presents and develops comprehensive knowledge of vehicular channel characteristics and proper vehicular channel models. The studied topics contain the propagation characteristics of vehicular communications, such as: a time-frequency non-stationary single-input single-output (SISO) vehicle-to-vehicle (V2V) non-geometry stochastic model (NGSM); a space-time non-stationary massive multiple-input multiple-output (MIMO) V2V regular-shaped geometry-based stochastic model (RS-GBSM); and a space-time non-stationary massive MIMO V2V irregular-shaped geometry-based stochastic model (IS-GBSM). Each is introduced, with characteristics then discussed in detail. Finally, this book discusses future research directions to inspire further investigation in the field of vehicular channels from three different perspectives. Presents knowledge of vehicular communication channel characteristics and proper vehicular communication channel models; Studies several topics that contain the propagation characteristics of vehicular communications; Includes research directions to inspire investigation in the vehicular channels from a variety of perspectives.