There is little room you can improve on efficiency nor is there much room for lowering the aero. A bigger pack seems to be the only way to get more range from my point of view. I don't think a 250 mile is a sweet point for such an expensive car. It might be the sweet point of triggering sales of a certain EV. Model S is far from a perfect car, lacking some range being the most important one as I can see. I'd agree 650 miles is too long for most people, however due to the slow "refill speed" of EV, longer range is still desirable.