Thanks to its open programmability and logically centralized control, the software-defined networking (SDN) paradigm presents new potentials for communication and networking management in vehicular networks and promises improved performances. The variety of applications delivered on the road like safety, traffic efficiency and infotainment, in addition to the diversity of developed SDN controllers, triggered the challenge to determine which controller can act better in which service. In this paper we conduct a performance comparison of four open source controllers (POX, Floodlight, ONOS and OpenDaylight) in terms of e2e delay in the context of safety applications in variable vehicular density environment. Experimental study done with advanced tools such as Iperf and Mininet-wifi indicates that ODL is the best in this context.