If 80 MPH is around 375 Wh per mile, then 200 miles of driving at that rate would consume 75,000 Wh, or 75 kWh of energy. If you presume that is a full battery pack, and that there is perhaps a 10% anti-brick protection... That would require an 83.333~ kWh battery pack. If you instead presume that is with a 20% buffer remaining after charging to 90%, then the full capacity would be... Something like a 119 kWh battery pack.
My first car was rated at an EPA 28 MPG. In actuality, it got around 32 MPG when filled with Premium fuel. Due to its efficiency and sizable gas tank, I could set the cruise control at 85 MPH, drive around 530-to-540 miles and still have 1-1/2 gallons of fuel left. No other car I've owned, or driven regularly, had such range. It would be spectacular to have such range in an EV on the highway.
But again, looking at the reality of how much energy that would be expended, and the state of battery technology for the near future, that is truly an unreasonable short term goal. Thus, I have no problem with Tesla Motors looking to satisfy their range goals under EPA ratings until that time comes. As many have said already, until you live the life of an EV on the road, you just don't know what you don't know. And everyone that says it isn't practical, it can't be done, that it's just too slow, and far too inconvenient, is ignoring all the facts that are before them. Unless they are simply using lowest common denominator preventive social maintenance to presume that people simply won't be able to manage the mental gymnastics of planning a road trip because they are just that dumb and will get themselves stranded.
Sure. There are plenty of dumb people. But I think that all it takes is a bit of education. Changing a few bad habits. And experiencing EVs on a daily basis. So that with practice, almost anyone with opposable thumbs and an IQ that is an order of magnitude above their sneaker size will be just fine.