Vehicular networks have emerged in the past years as one of the most promising technologies in the context of Intelligent Transportation Systems. Several applications have recently been envisaged to improve the lives of citizens in different ways, particularly in the field of safety. In this work we focus on a different direction by leveraging on vehicular communication technologies and software-defined networking (SDN) to achieve a solution able to improve the travel time of emergency vehicles (EVs) when traveling in urban environments. In particular, we devise a solution where the route to be followed by EVs is shared with an SDN-enabled infrastructure, being then smartly rebroadcasted using those roadside units (RSUs) that fall within the region the EV will pass by in a near future. This way, standard vehicles that are ahead of the EV are notified about its arrival, and clear the required lane to facilitate a faster and obstacle free path for the EV's journey. Simulation experiments based on the SUMO traffic simulator for the city of Valencia, Spain, show that, if properly tuned, the proposed solution is able to reduce the travel time of EVs by nearly 15%, while maintaining the travel time of other vehicles mostly unaltered.