The growing development and use of on-board electronic devices in motor vehicles have increased the need for advanced diagnosis. In parallel, information channels are now at disposal for communication between the car and the outside world for comfort and safety applications. This paper aims in a first step at presenting the emerging needs in electronic car remote diagnosis, and a state of the art in the various telecommunication technologies; in a second section, it aims at studying possible applications of telediagnostics, as it takes advantage of both new on-board electronic architectures and communication structures to implement advanced diagnostic functions. Three applications are discussed in detail, with respect to the need for advanced diagnosis functions as well as the relevant associated communication structures. Consequences on the on-board electronic architecture and implementation costs will also be considered.