Operational data generated and used in a vehicle to control various vehicular systems is temporarily stored in a data buffer in the vehicle. A processor in the vehicle is configured to detect anomalous conditions, which can be based on predefined fault codes or user defined conditions (based on a single parameter or a combination of parameters). Whenever such an anomaly is detected, a diagnostic log is conveyed from the vehicle to a remote location. Such a log will include the detected anomaly, and buffered operational data. In at least one embodiment, the diagnostic log includes buffered operational data collected both before and after the anomaly. The diagnostic log is analyzed at the remote location to diagnose the cause of the anomalous condition, so a decision can be made as to whether the vehicle requires immediate repair, or whether the repair can be scheduled at a later time.