I had the same observation a while back when I started taking logs on the consumption for several days. My conclusion is that the trip meter grossly understates the energy consumption (something like 80%). I even start to suspect that the trip meter is only measuring the drive train energy consumption, not including any accessory power usage for the car, ex AC, entertainment, lighting, door operation etc.
Take a look how much KWh added after each charging session (flip between rated range and battery percent in settings), you will see the real battery consumption.