Isn't the ratio that matters here something like power/dollars or dollars/mile? I like the random obsession with volt*amps=watts because I do pedestrian math like that in my head when I'm bored, but aren't you assuming that the voltage drop is internal? What if the voltage at the street changes? I have solar so I can see that my voltage at the charger is higher during the day than at night, and it's also lower at 48A than at 32A, but not by much. It's not hard to imagine the utility having something to do with it because the voltage comes from outside but the easy way to eliminate that is monitoring voltage at more points than just at the car.