This manuscript surveys a variety of topics related to the security of connected vehicles and their associated services, often referred to as telematics. Current challenges as well as emerging and future security risks are discussed. A number of specific technologies and implementations are discussed, such as Next Generation Telematics Patterns, KeeLoq, vehicular ad hoc networks, and controller area network. Principles and practices are outlined to counter or minimize risks associated with the existing and potential attack vectors as well as reducing risks both on the internal vehicle network and the telematics service delivery platforms.