i know its not a very interesting or important topic, but i was having this conversation with a buddy of mine who says downshifting instead of braking wastes more gas. I feel as it does not, seeing as how i'm not pressing the throttle at all. I have tiptronic, so engaging the clutch at a proper rpm (which would invovle pressing the throttle) does not apply here.
My friends arguement is that in order for the engine to slow the car down (due to the sudden increase in RPM's), there must be an input of energy. The slowing of the car expels energy, so according to physics, there must be some sort of input of energy, i.e. from the fuel.
What do u guys think??