Vehicular ad hoc networks (VANETs) are characterized by high mobility of vehicle nodes, intermittent connectivity, and rapid dynamic topology. Data to be disseminated can hardly be kept within a target area, and therefore cannot provide continuous services for the vehicles passing by. Motivated by the fact that there are large amounts of roadside parked vehicles in urban areas, this paper proposes a parked-vehicle assisted data dissemination (PADD) paradigm for vehicular ad hoc networks (VANETs). In PADD, the parked vehicles in the target area are managed on the basis of parking cluster, the data to be disseminated are forwarded from the data source to the selected parking clusters, and the pub/sub scheme is adopted to achieve data dissemination within one hop of the parking cluster. Theoretical results illustrate the effectiveness of the proposed approach, and meanwhile simulation results based on a real city map and realistic traffic situations show that PADD achieves a higher delivery ratio with lower network load and reasonable transmission delay.