The rapid evolution of wireless communication capabilities and vehicular technology would allow traffic data to be collected and disseminated by travelling vehicles in the near future. Vehicular Ad hoc Networks (VANETs) are self-organizing networks that can support different types of traffic information systems without requiring fixed infrastructure or centralized administration. Since traffic data is of public interest and usually benefits a group of users rather than a specific individual, it is more appropriate to rely on a broadcasting scheme for data dissemination in VANETs. However, broadcasting in dense networks suffers from a high percentage of redundant data that wastes the limited radio channel bandwidth. Moreover, packet collisions may lead to the broadcast storm problem since a large number of vehicles in the same vicinity may rebroadcast the same data nearly simultaneously. A common employed solution to deal with such scalability issues is reducing the percentage of redundant data. This is typically done by selecting only some of the vehicles to relay data packet as opposed to letting every single vehicle rebroadcast it. In this work, we propose involving the high mobility feature of VANETs to improve scalability in data dissemination, by relying on the speed of travelling vehicles to determine the rebroadcasting probability.