Traffic congestion, pollution and changes in climate are the reasons for a growing need for a advanced real-time traffic-related information systems and services. Safety and mobility can, however, be jeopardized by poor highway design and construction or by operating procedures which allow unsafe driving conditions e.g. construction work zones, incident management or response to emergencies caused by adverse weather. This paper presents the CARLINK (Wireless Platform for Linking Cars) project. The aim of the project was to develop an intelligent wireless traffic service platform between cars supported with wireless roadside units, and this goal was successfully completed. The main outcomes of the project were the platform itself, with real-time local road weather and traffic data applications, urban transport traffic management and information broadcasting/sharing applications, fast connectivity and routing schemes for ad-hoc networking and hands/eyes free applications that enable the driver to interact with the information system. The network simulations, communication tests and weather service prototypes showed that a new kind of wireless communication environment can be created. Preliminary estimation shows also that with this platform in full-scale operation the fatal traffic accidents can be clearly reduced.