Usually when you put the pedal to the metal the engine straight away goes into higher revs which essentially causes you to use more fuel. The ECO mode (fuel saving mode) on the HIKE IT slows the response of this down, which stops the engine responding in that way. The slower response allows your engine to get to the right speeds without using as much fuel. Which means that instead it creates a smoother acceleration rather than the higher revs. This function in turn can give you up to 20% more distance for the same amount of fuel.