From what i've read about the DBW its for emissions and smoother throttle control/response. Our lancer has it, when i had the old ke30 i could notice the difference between them, its the same thing with the father-inlaws astra. Hard to explain but there's no, urm, edgyness (harshness) on the lancers throttle. And on the plus side of the DBW is that when the cruise control is set the speed stays more or less the same on the flats, up a slope and down a slope there's very little, if any, run-away on the speed of the car. The cars i've driven that had cruise would run-away on a downwards slope which would mean i'd have to do some braking and in turn cancelling the cruise control.