In vehicular networks, the instantaneous connectivity between any two consecutive vehicles is a function of both the headway distance between them and the communication channel characteristics. We derive a generalized analytic expression for vehicle-to-vehicle link connectivity probability in highway vehicular networks that considers the change in vehicle headway distribution under different traffic conditions. The introduced formulation is derived under the Nakagami-m small-scale fading model which captures a wide range of small-scale fading conditions in freeway vehicular networks and was shown to well fit the empirical data. This formulation is of interest in analyzing and simulating vehicular communication systems.