There shouldn't be a difference in MPG whether you blip the throttle on a downshift or the car does it for you. I can see, however, that because the car has such precise blips on downshifts that you would be more willing blip it at a higher RPM (because you don't have to worry about not matching the RPMs correctly), which means you are probably accelerating harder than your normally would. IDK...just a thought.

i think you are right... i noticed that today