A control method for a vehicle, the vehicle comprising: - an electric power generator structured to generate electric power and supply the electric power to a battery; - an electric motor structured to be driven by electric power from the battery or from the electric power generator, and drive the vehicle; - an internal combustion engine structured to drive the electric power generator, and vary an air fuel ratio; - a vehicle speed measuring section structured to measure vehicle speed of the vehicle; and - an accelerator operation quantity measuring section structured to measure an operation amount of an accelerator pedal of the vehicle or an operation speed of the accelerator pedal; wherein: - the control method comprises, under a condition that an SOC of the battery is greater than or equal to a predetermined SOC threshold value which is nonzero, performing a standby operation of the internal combustion engine for standby to assist electric power supply to the electric motor, and - the standby operation is implemented by performing a lean combustion operation at a first operating point that is lower in engine power output than a second operating point set for charging the battery in response to a condition that the SOC of the battery is less than the SOC threshold value, characterized in that - intake pressure of the internal combustion engine at the first operating point is greater than or equal to a predetermined intake pressure threshold value and - the standby operation is performed in response to a condition that the vehicle speed is greater than or equal to a predetermined vehicle speed threshold value which is nonzero, and the operation amount of the accelerator pedal or the operation speed of the accelerator pedal is greater than or equal to a corresponding one of a predetermined operation amount threshold value which is nonzero and a predetermined operation speed threshold value which is nonzero. the vehicle comprising: - an electric power generator structured to generate electric power and supply the electric power to a battery; - an electric motor structured to be driven by electric power from the battery or from the electric power generator, and drive the vehicle; - an internal combustion engine structured to drive the electric power generator, and vary an air fuel ratio; - a vehicle speed measuring section structured to measure vehicle speed of the vehicle; and - an accelerator operation quantity measuring section structured to measure an operation amount of an accelerator pedal of the vehicle or an operation speed of the accelerator pedal; - an electric power generator structured to generate electric power and supply the electric power to a battery; - an electric motor structured to be driven by electric power from the battery or from the electric power generator, and drive the vehicle; - an internal combustion engine structured to drive the electric power generator, and vary an air fuel ratio; - a vehicle speed measuring section structured to measure vehicle speed of the vehicle; and - an accelerator operation quantity measuring section structured to measure an operation amount of an accelerator pedal of the vehicle or an operation speed of the accelerator pedal; wherein: - the control method comprises, under a condition that an SOC of the battery is greater than or equal to a predetermined SOC threshold value which is nonzero, performing a standby operation of the internal combustion engine for standby to assist electric power supply to the electric motor, and - the standby operation is implemented by performing a lean combustion operation at a first operating point that is lower in engine power output than a second operating point set for charging the battery in response to a condition that the SOC of the battery is less than the SOC threshold value, - the control method comprises, under a condition that an SOC of the battery is greater than or equal to a predetermined SOC threshold value which is nonzero, performing a standby operation of the internal combustion engine for standby to assist electric power supply to the electric motor, and - the standby operation is implemented by performing a lean combustion operation at a first operating point that is lower in engine power output than a second operating point set for charging the battery in response to a condition that the SOC of the battery is less than the SOC threshold value, characterized in that - intake pressure of the internal combustion engine at the first operating point is greater than or equal to a predetermined intake pressure threshold value and - the standby operation is performed in response to a condition that the vehicle speed is greater than or equal to a predetermined vehicle speed threshold value which is nonzero, and the operation amount of the accelerator pedal or the operation speed of the accelerator pedal is greater than or equal to a corresponding one of a predetermined operation amount threshold value which is nonzero and a predetermined operation speed threshold value which is nonzero. - intake pressure of the internal combustion engine at the first operating point is greater than or equal to a predetermined intake pressure threshold value and - the standby operation is performed in response to a condition that the vehicle speed is greater than or equal to a predetermined vehicle speed threshold value which is nonzero, and the operation amount of the accelerator pedal or the operation speed of the accelerator pedal is greater than or equal to a corresponding one of a predetermined operation amount threshold value which is nonzero and a predetermined operation speed threshold value which is nonzero.