Utility of being able to drive 500 miles and then 'recharge' in five minutes = lots.
I don't really understand the necessity of this. Realistically, you're gonna be driving at most 70mph, more likely averaging 50-60 over a long journey. You can reasonably do 4 hours before you need to stop for lunch, and another 4 in the afternoon before you're going to want to eat dinner. Both of those meals are gonna take you half an hour.
That means that a range of between 200 and 280 miles is sufficient for pretty much any form of driving save for utter insanity driving all through the night, and frankly, forcing you to stop for half an hour every few during that time I regard as a good thing, not a bad.
That said, I do think the tesla's current ~267mile range (assuming 85->90kWh scales linearly) is a tiny bit on the short side. If they managed to get the thing to 300, that would be pretty much sufficient for all forms of driving.