This paper investigates the network performance for information dissemination via broadcasting in Vehicular Ad Hoc Networks (VANETs). The major challenge of broadcasting is to disseminate messages over the intended regions with low cost while to ensure the reliability of message delivery. To minimize the broadcast cost in delay tolerant data dissemination, this paper proposes a method, called Segcast, along with an analytical model to easily compute the broadcast cost and end-to-end delay according to the input parameters describing the network environment, such as the vehicular density and the transmission range. In this method, an appointed vehicle, named Segcast agent, is selected to transmit a broadcast message to oncoming disconnected vehicles located on a given road segment. Compared with the state-of-the-art approach, Segcast consumes much less network bandwidth and significantly improves the survivability of the message dissemination in large areas that have intermittent connectivity. Simulation results are presented to demonstrate that Segcast can perform efficient broadcasting for delay tolerant applications.