Emerging Vehicular Ad-Hoc Networks (VANET) have the potential to improve the safety and efficiency of future highways. This paper reviews recent advances in wireless communication technologies with regard to their applications in vehicular environments. Four basic demands of future VANET applications are identified, and the research challenges in different protocol layers are summarized. Information dissemination is one of the most important aspects of VANET research. This paper also discusses the primary issues in information dissemination from an information-centric perspective, and provides two case studies. Finally, future research directions and possible starting points for new solutions are considered.