I have the non-NAV version with the much simpler energy flow display. I'm not saying that it will never be reached, but probably under fairly rare conditions. For instance a long time coasting down hill using regenerative braking. Under normal driving conditions the engine will also regenerate the battery. I don't believe the computer will allow the engine to charge it to the top of the display. I have had times that I've seen the display get to within one bar of the top, but that's usually when it was already pretty high and I then coast for a while.