I spend way too much time on this website tracking all that has been said about the Model S but I have not heard any discussion yet about the "missing 5 kWh." When adding 20 kWh, by moving up from the 40 kWh pack to the 60 kWh pack, range jumps by 70 miles from 160 to 230 miles. This is despite a weight increase of approximately 400 pounds as the battery pack moves from roughly 6,000 cells to roughly 9,000 cells. But when adding 25 kWh, by moving up from the 60 kWh pack to the 85 kWh pack, range jumps the same 70 miles from 230 to 300 miles. And this occurs without an increase in weight but is instead achieved by using a better, more advanced, battery cell chemistry. Why does that extra 5 kWh not produce an extra 17.5 miles in added range especially since weight is not increasing? All these range estimates are calculated at a constant 55 mph. Are all kWh not created equal?