I noticed today when I was partially charging my new P8 that the charger was recording more KWhs than would have gone into the car. I was going from 70% to 90%, so 15 KWh. However, my home charger reported delivering 16.7 KWh. I noticed something similar with a short term rental electric car. Is this normal behaviour? Could it be related to difficulties related to charging in the higher % ranges - maybe requiring more energy to condition the battery or something?