Vehicle environment is a good testbed to investigate Internet mobility technologies. Based on testing of building, protocol implementation details and problems to deploy it will be clarified. This paper describes them. InternetCAR Project had already done a testing to connect vehicles to the IPv6 Internet. Some applications includes vehicle diagnosis and teleconference, are implemented on the test system. The test system has following functions: 1) several communication media with a media switching technology, 2) MobileIPv6 function for continuous connectivity, and 3) network mobility (NEMO) [1][2] function to provide continuous Internet connectivity for an in-vehicle network. This paper introduces problems to develop InternetCAR testing system. Our design and solutions also described.