The present invention relates to a vehicle comprising: a third control unit for sensing the gear being placed into a parking mode and the removal of an ignition key; a control unit including a temperature-setting part for setting a temperature for a cooling or heating operation, a second sensor for sensing whether or not an indoor temperature has reached the temperature for the cooling or heating operation, a selection switch for enabling a user to select a cooling mode or a heating mode, and an operating switch for operating a cooler or a heater in accordance with the selected cooling mode or heating mode; a main battery for storing power generated by a generator; a first auxiliary battery and a second auxiliary battery for storing surplus power of the main battery; a first control unit interconnected between the main battery and the first and second auxiliary batteries so as to selectively supply the surplus power of the main battery to the less-charged side of either the first auxiliary battery and the second auxiliary battery; a second control unit interconnected between the output ends of the first and second auxiliary batteries and the cooler and the heater so as to selectively supply the charged power of the first and second auxiliary batteries to the cooler and the heater; an air-circulating device connected to one end of the second control unit so as to be operated by the driving power of the first and second auxiliary batteries; a carbon dioxide sensor connected to the other end of the second control unit so as to sense the concentration of carbon dioxide in an indoor area of the vehicle; and a converting switch interconnected between the first control unit and the second control unit so as to supply the power of the first and second auxiliary batteries to a starter motor upon the occurrence of a discharge of the main battery.