A number of devices, including sensors, mobile phones, and various computers will be deployed in next generation vehicles, and interconnected on a local network. These vehicles will be connected to the Internet as both a step toward ubiquitous computing and as a means to meet Intelligent Transportation Systems (ITS) needs. For doing so, the communication system requirements are investigated in the InternetCAR project, particularly IPv6 and network mobility support which is mandated to maintain ongoing sessions as the in-vehicle embedded network changes its point of attachment to the Internet topology. In order to deal with the specific issues raised by network mobility, which contrast with traditional work on host mobility, the IETF NEMO working group has been set up. The initial proposition for doing so, Prefix Scope Binding Updates, is implemented in our testbed, designed to demonstrate the proposed communication system.