When a vehicle power demand is less than a threshold value, which is set to or around a lower limit of a relatively efficient drive range of an engine and when an engine drive demand is set ON because of requirement for heating by an air conditioning system, the drive control of the invention sets the threshold value to an engine power demand and sets a higher level than a standard level to a maximum SOC (state of charge) of a battery. This drive control starts load operation of the engine with charge of the battery. The load operation of the engine desirably improves the fuel consumption of the vehicle, compared with independent operation of the engine.