Abstract: A flexible protective cover for an automotive vehicle is provided with an anchorage mechanism that is inserted through a door opening or trunk opening. When the door or trunk lid is closed and locked, the anchorage mechanism is trapped within the vehicle interior space so that it cannot be pulled out to remove the cover from the vehicle. The anchorage mechanism is preferably a hollow air-filled structure having a whistle or siren mounted in such a position that when an external pulling force is exerted on the anchorage mechanism air is forced out of the air-filled structure through the whistle or siren, thereby producing an audible alarm signal.