Little disappointed to learn that one is not able to upgrade the onboard charger from a 48AMP to a 72AMP on current 75D cars. Was hoping as the 75 D Model S & X are premium cars that they would also have this option available at time of ordering or after the fact. Does anyone have any idea why this might be. I once heard the wiring was different on the 75 vs. 100 models. Not sure if this is correct. If anyone has any ideas please let me know. I expect for the premium one pays for the MS & MX that they offer a 72AMP option not offer it with the same charger as in the considerably cheaper Model 3. Seems a backwards move.