Vehicle-to-Grid (V2G) solutions are gradually being deployed, offering the potential to provide ancillary services, enhance grid stability, and generate revenue for Electric Vehicle (EV) owners. Aggregators play a central role by coordinating EV fleets to participate in electricity markets. However, their scheduling strategies often rely on aggregated fleet data. This approach can obscure behavioral diversity among individual users and lead to overestimation of fleet flexibility, especially in intraday electricity markets, where short-term availability is critical. To better understand these discrepancies, this study explores the potential of V2G systems to participate in intraday electricity markets through a detailed analysis of real-world residential EV operational data from Germany. Statistical methods are applied to assess the role of private EV fleets in short-term market environments by analyzing connection status, plug-in and plug-out patterns, and availability across different time scales. Key indicators, such as arrival and departure behaviors, connection windows, and fleet size, are analyzed to determine when EVs can provide flexibility to the grid. The results highlight significant differences between fleet averages and individual behaviors, emphasizing the importance of detailed statistical analysis for optimizing V2G market strategies and supporting the integration of EVs into electricity markets.