Equilibrandt
I suspect this is the source for the numbers, or at least close.
EVs Explained: Charging Losses
When adding energy to an EV's battery pack, more is expended than what makes it into the pack. How much varies considerably depending on the electrical output and ambient conditions.
Because the battery is more complicated than a simple container. A rough expectation is that your EV may use as much as 12 to 15 percent more energy than what you add back to the battery. Some energy is written off to what's known as "transmission loss," some is converted to heat, and some is used to keep the battery at the right temperature during charging.
https://www.caranddriver.com/feature...arging-losses/
This doesn't take into account the transmission loss in the charger itself or the transmission loses in the grid. Your point about outside influences in this is quite true IMO. At the end of the day the only real comparison is the cost per mile of the EV vs the ICE. Both sides of this argument have a tendency to shade the truth or commit the sin of omission.