An autonomous vehicle (1000, 2100, 2110), in the following referred to as AV, comprising: an internal sensor configured to detect an object within the AV; and a sensor configured to determine a distance of a recent occupant to the AV; and a processor configured to execute instructions stored on a non-transitory computer readable medium to: detect, based on sensor information, the object within the AV; in response to determining that the recent occupant to the AV is outside the AV and is touching a door of the AV and that the object is within the AV, vibrating a part of the AV; select, based on the recent occupant being outside of the AV and the recent occupant being not beyond a threshold distance from the AV, a first notification modality, including an external audio signal, for sending a message to the recent occupant, the message indicating that the object is left by the recent occupant in the AV; send, using the first notification modality, the message to the recent occupant (512,516); select, based on the recent occupant being outside of the AV and the recent occupant being beyond the threshold distance from the AV, a second notification modality, including a text message and/or a voice call, for sending the message to the recent occupant; and send, using the second notification modality, the message to the recent occupant. an internal sensor configured to detect an object within the AV; and a sensor configured to determine a distance of a recent occupant to the AV; and a processor configured to execute instructions stored on a non-transitory computer readable medium to: detect, based on sensor information, the object within the AV; in response to determining that the recent occupant to the AV is outside the AV and is touching a door of the AV and that the object is within the AV, vibrating a part of the AV; select, based on the recent occupant being outside of the AV and the recent occupant being not beyond a threshold distance from the AV, a first notification modality, including an external audio signal, for sending a message to the recent occupant, the message indicating that the object is left by the recent occupant in the AV; send, using the first notification modality, the message to the recent occupant (512,516); select, based on the recent occupant being outside of the AV and the recent occupant being beyond the threshold distance from the AV, a second notification modality, including a text message and/or a voice call, for sending the message to the recent occupant; and send, using the second notification modality, the message to the recent occupant. detect, based on sensor information, the object within the AV; in response to determining that the recent occupant to the AV is outside the AV and is touching a door of the AV and that the object is within the AV, vibrating a part of the AV; select, based on the recent occupant being outside of the AV and the recent occupant being not beyond a threshold distance from the AV, a first notification modality, including an external audio signal, for sending a message to the recent occupant, the message indicating that the object is left by the recent occupant in the AV; send, using the first notification modality, the message to the recent occupant (512,516); select, based on the recent occupant being outside of the AV and the recent occupant being beyond the threshold distance from the AV, a second notification modality, including a text message and/or a voice call, for sending the message to the recent occupant; and send, using the second notification modality, the message to the recent occupant.