The reading on the dial is…
The reading on the dial is just a reference to a threshold. Some manufacturers change the 0% threshold over the life of the car to compensate for the fade of the battery. I understand that in the evacuation of a city in Florida for a hurricane a few years back, Tesla logged into all the cars and opened up the full capacity of the battery so people could evacuate. people who thought they had 20% battery suddenly found they had 45%.