A vehicle system includes at least one autonomous driving sensor programmed to output environment signals representing an environment around an autonomous vehicle and object detection signals representing an object or person on an exterior surface of the autonomous vehicle. The vehicle system further includes an autonomous mode controller programmed to autonomously control the autonomous vehicle in accordance with the environment signals output by the autonomous driving sensor, detect the object or person on the exterior surface of the autonomous vehicle in accordance with the object detection signals, and limit autonomous operation of the autonomous vehicle in response to detecting the object or person on the exterior surface of the autonomous vehicle.