This paper proposes a STAR-RIS aided integrated sensing and communication (ISAC) scheme for high mobility scenarios. The STAR-RIS is mounted on the exterior of a vehicle to enhance communication for in-vehicle user equipment (UE) and simultaneously track and sense the vehicle. The system employs a novel transmission structure with orthogonal precoders and combiners at the base station (BS) and roadside units (RSUs) for channel parameter extraction. The near-field static channel model between the STAR-RIS and UE, as well as the far-field time-frequency selective channel model between the BS-RIS-RSUs, are characterized. Using the multidimensional orthogonal matching pursuit (MOMP) algorithm, cascaded channel parameters (delays, Doppler shifts, angles of arrival, and departure) are extracted at the RSUs, enabling vehicle localization and velocity measurement. The reflection and refraction phase shifts of the STAR-RIS are designed based on sensing results to improve signal strength for both RSUs and the UE. A trade-off design for sensing and communication is proposed by optimizing the energy splitting factors of the STAR-RIS. Simulation results validate the feasibility and effectiveness of the proposed STAR-RIS aided ISAC scheme. The system addresses the challenges of high mobility scenarios, including large-scale Doppler shifts and signal blockage by the vehicle body, and enables efficient communication and sensing performance.This paper proposes a STAR-RIS aided integrated sensing and communication (ISAC) scheme for high mobility scenarios. The STAR-RIS is mounted on the exterior of a vehicle to enhance communication for in-vehicle user equipment (UE) and simultaneously track and sense the vehicle. The system employs a novel transmission structure with orthogonal precoders and combiners at the base station (BS) and roadside units (RSUs) for channel parameter extraction. The near-field static channel model between the STAR-RIS and UE, as well as the far-field time-frequency selective channel model between the BS-RIS-RSUs, are characterized. Using the multidimensional orthogonal matching pursuit (MOMP) algorithm, cascaded channel parameters (delays, Doppler shifts, angles of arrival, and departure) are extracted at the RSUs, enabling vehicle localization and velocity measurement. The reflection and refraction phase shifts of the STAR-RIS are designed based on sensing results to improve signal strength for both RSUs and the UE. A trade-off design for sensing and communication is proposed by optimizing the energy splitting factors of the STAR-RIS. Simulation results validate the feasibility and effectiveness of the proposed STAR-RIS aided ISAC scheme. The system addresses the challenges of high mobility scenarios, including large-scale Doppler shifts and signal blockage by the vehicle body, and enables efficient communication and sensing performance.