Well, I had a long drive but plenty of time to do it so I decided to see how good of gas mileage I could get on the Prius. As I started my trip I was headed in to a blizzard with terrible head winds, so the first half of my trip didn't go so well on the mileage experiment. But then when I refilled in Winnemucca I reset the mileage and then proceeded on the back roads to see how high I could go. It seemed that the trip from Winnemucca to Oregon was mostly up hill. Somewhere before I got to Klamath Falls I realized I had to give up the experiment if I was going to get checked in to my room in time. So I stopped and got a picture of the results, 75.4 MPG.
I figured the rest of the way my mileage would go down real bad as I had to go over a mountain range and I had to drive fast to get there in time. However when I got to Ashland my over all mileage was still over 73 mpg.