A vehicular ad hoc network, or VANET, is a technology that uses moving cars as nodes in a network to create a mobile network. Vehicular networks are becoming a crucial component for the future intelligent road traffic management system. The key advantages are improved knowledge based real time traffic signaling systems, improved safety of vehicular traffic and reduced vehicular emissions. VANETs can be seen as self-organizing autonomous system which can distribute traffic and emergency information to vehicles in a timely manner. VANET is evolving as one of the practical applications of MANETs in the future. The goal of VANET is to develop a vehicular communication system to provide quick and cost-efficient distribution of data for the benefit of passenger safety and comfort. The key difference of VANET and MANET is the special mobility pattern and rapidly changeable topology. It is not effectively applied the existing routing protocols of MANETs into VANETs. In this investigation, we mainly survey new routing results in VANET. With the consideration of multi-hop forwarding and carry-and-forward techniques, min-delay and delay-bounded routing protocols for VANETs is discussed. The key challenge is to overcome these problems to provide routing protocols with the low communication delay, the low communication overhead, and the low time complexity. The challenges, application, attacks and perspectives of routing protocols for VANETs are finally discussed.