Safety systems for vehicles, primarily passenger vehicles, comprising automated systems and methods for preventing entrapment of children, disabled, aged or infirm persons, or pets from being trapped in closed vehicles left in the sun, so that they will not suffocate from the heat. The invention is characterized by use of one or more systems to sense the occupancy state and temperature inside the vehicle passenger or load space, and provide one or more outputs which can selectively be employed to provide interior and exterior warning of a trapped passenger in a dangerously hot car to permit rescue, and/or to activate vehicle electro-mechanical systems to relieve the heat, such as rolling down windows, unlatching seat belts, unlocking doors, starting the car and/or fans or air conditioning systems and the like. The exterior warnings may be any suitable warning, such as sounding the car horn or alarm siren, flashing head, tail or special lights, placing an emergency call via a vehicle dedicated cell phone, CB radio, GPS system, or the like.