Most electric cars have a so called Guessometer, sometimes referred to as the GOM, which displays the remaining range in the battery as a guess based on the remaining percentage and current and past driving conditions, plus any other loads on the car like heating, wipers etc.
Often on a long journey, the remaining range will actually increase as the car and battery warm up and therefore efficiency increases
Remember, batteries don't store miles, they store energy as electric charge which can be measured as a percentage fairly accurately.
Here we see how to reset the MG4 guess o meter to the factory average of 3.7 miles per KWh.
