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.