Pretty much every car gets bad gas mileage above 80 miles per hour. That is a pointless comparison, IMO. I am skeptical that the Prius will do that much better at such high speeds, especially going over mountains and maintaining 70+. Probably the Insight would do the best, simply due to aerodynamics and the fact it is so light. But still, why drive in a non-fuel efficient manner and then complain about bad gas mileage?

Also, while a more powerful engine may do better at high speeds, they do worse at low speeds, so the trade-off is most likely going to be for the worse. People with the HAH seem to be struggling to get 30+ MPG in the first place, so in that light your mileage numbers don't look that bad.