You know what would be a killer feature? If the Model-S had an up-to-date map of the locations of all of the chargers in the network, and it monitored how close you were to the closest one and compared it to the remaining range you had. It would be able to warn you if your range started getting dangerously far from a charger "lifeline" and even give you emergency GPS directions to the nearest charger as soon as the range got within say...5% of that minimum.