This paper presents a dual-mode sentinel surveillance architecture for shared vehicles that combines low-power inertial event triggering with low-rate fisheye vision and temporal decision logic. Unlike conventional sentry systems based on continuous vision or motion-only alarms, the proposed approach prioritizes energy efficiency while preserving contextual awareness. We introduce SentinelCAR, a real-world fisheye dataset comprising 18308 images annotated for activity-aware human presence around