A method for controlling activation of a power source of a hybrid electric vehicle. A hybrid electric vehicle has first and second power sources connected to a motor. The motor is connected to a transmission adapted to drive a vehicle wheel. The method includes comparing a vehicle speed value to first and second threshold values. If the vehicle speed value is less than the first threshold value, then the method determines whether a vehicle brake is released. If the vehicle speed value is greater than the first threshold value and less than the second threshold value, the method determines whether additional acceleration is demanded. The power source is activated if additional power is demanded or if the vehicle brake has been released. The power source is deactivated if the brake is engaged or if additional power is not demanded.