I'm curious about that comment. I've heard the same mentioned a couple of times. I don't doubt it, especially given you've measured output and miles and come up similarly.
However, I wonder about something. When the car is driving, I was assume it's possible to measure the kWh used. However, while measuring in the car while driving, wall-to-wheels doesn't seem to make sense to me. How can the loss between the wall and vehicle be measured and/or figured into the figure presented on the dash? I certainly believe there is loss in the charging process, and my understanding is it's in the 18-20% area. But, how would the be figured in when measured in car use?