Abstract: A .Iadd.system and .Iaddend.method .[.of.]. .Iadd.for .Iaddend.automatically starting and stopping an engine of a .[.truck.]. .Iadd.vehicle .Iaddend.to conserve fuel while maintaining the engine in a ready-to-start condition, and while controlling the temperature of .[.a truck sleeper unit.]. .Iadd.an interior portion of the vehicle.Iaddend.. The method includes the steps of selecting predetermined system parameters .[.via a password accessible interactive program, providing a first switch for selecting an automatic engine start-stop operating mode, providing a second switch for selecting an automatic temperature control mode for the truck sleeper unit, and providing safety apparatus which indicates when the truck engine may be safely operated in the automatic engine start-stop operating mode..]. The method further includes the step of overriding the .[.ignition switch.]. .Iadd.operator .Iaddend.control of the engine in response to a predetermined condition when .[.the.]. .Iadd.a .Iaddend.