I think that tesla is not using efficiently energy from battery packs, on D models if you have two motors and two transmissions then why not to use them at different speed separately and at peak efficiency. If tesla would use only rear motor to speed of 55mph at standard 9.87 gear ratio and front from speed of 55mph at gear ratio 4.2, then 60D range would nearly duble range and be like standard 100D at ever day use. I think this would make huge differnece in ev market and make Tesla more even more efficient. As we can see tesla is nearly all time using just rear motor- 2:14 at this video, so if it uses rear to 55mph and just front with modified gear ratio to 4.2 from speed of 55mph, than the range would nearly duble in every day use. Also aerodynmics should be taken in consideration, but i think car would nearly double the range at highway speeds.