Digital Twin in Vehicular Communications: Challenges and Opportunities

Digital twins (DTs) are increasingly studied together with vehicular communications, but the literature spans different twinned entities, synchronization assumptions, computing placements, and levels of experimental evidence, which makes results difficult to compare. This survey provides a communication-centric review of DT-enabled vehicular systems. We first introduce an operational definition for a vehicular DT and distinguish a synchronized DT from a static simulator or digital model. We then organize the field according to twin granularity, physical–virtual synchronization, vehicle–edge–cloud placement, enabling V2X technologies, and measurable evaluation dimensions. The standardization discussion is updated from DSRC and IEEE 802.11p through 5G-Advanced and ongoing 3GPP work toward 6G, together with recent digital-twin and network-digital-twin standards. Rather than treating reported benefits as established outcomes, we compare the assumptions, metrics, evidence, limitations, deployment constraints, and safety and security implications of representative studies. Finally, we identify research priorities involving synchronization staleness, twin placement and migration, communication–computation–fidelity tradeoffs, validation and uncertainty, interoperable data models, lifecycle management, and safety-aware closed-loop operation. The survey is intended to provide researchers and practitioners with a structured basis for deciding when DT techniques are appropriate for vehicular communication systems and how such systems should be evaluated.