The car will surely do EPA mileage in EPA conditions and at EPA speeds. The mileage of the P85D will not be as good as the 85D and the buyers know this going in.
Is that what they know? All November, buyers were told 275 miles, at 65mph. Rob says EPA is "bogus nonsense". What if people like Rob can't get close to 275, at 65mph? Despite your rational understanding of mechanical efficiency, it isn't the rationale some of these buyers probably used. Maybe the acceleration will make all better.