Vehicular ad hoc networks (VANETs) are characterized by dynamic behavior and unique characteristics that contribute to the complexity of network connectivity and reachability, thereby posing substantial challenges to achieving efficient data transmission. While one avenue for understanding these network properties involves the application of time-varying graphs, comprehending such methods may be hindered by absence of well-defined analogies to established properties of static graphs. Thereby, this study addresses this gap by exploring the properties of time-varying graphs as a means to depict network characteristics, aiming to enhance data dissemination efficiency within vehicular networks assisted by unmanned aerial vehicles (UAVs). Considering delay-sensitive data dissemination, we integrate dissemination delay into the time-varying graph, introducing the concept of a delay-constrained time-varying graph (DTVG). In this context, a data dissemination problem is formulated to optimize data transmission utility. To address this problem, we propose a novel data dissemination algorithm leveraging insights from -token dissemination problem. Theoretical analysis is employed to derive both upper and lower bounds of our proposed algorithm. Simulations are conducted for validating the feasibility of characterizing dynamic networks based on time-varying graphs. Finally, the effectiveness of our proposed approach is demonstrated through the evaluation of metrics such as dissemination delay, delivery ratio, and network throughput.