If you are expending more energy by depressing the gas pedal all the time, it would go against the conservation of energy in one sense. Your sense of speed is going at the same pace, and the force that you are applying to the pedal is the same, so you are applying the same pressure, so there would actually be no change in the force. If you were to terminate, for any reason, curves, speed limit changes, something on te road, this is where your conservation of energy would come in because you are changing the pressure and the force.
