This book includes selected papers from the fourth International Conference on Smart Vehicular Technology, Transportation, Communication and Applications (VTCA 2021), held in Chengdu City, Sichuan Province, China, during May 22-24, 2021. The conference is technically co-sponsored by Southwest Jiaotong University, Shandong University of Science and Technology, Fujian University of Technology, and Minjiang University. The book includes research works from engineers, researchers, and practitioners interested in the advances and applications in the field of vehicle technology and communication. The book covers four tracks, namely (1) vehicular networking security, (2) vehicular electronics, (3) intelligent transportation systems, and (4) smart vehicular communication networks and telematics.