I’ve punched in the figures so far, which represent our road trip mileage (plus a bit of last minute Cambridge noodling around).
The car was fully laden for the whole of our journey (I could only just see out the rear window and the back seats were folded down). We had the air conditioner / heater on auto pretty much all the way, and I used cruise control whenever possible. We also took the car up a couple of mountains while fully laden; over 6,000 feet up. Hence, these are basically worst case real world figures for Prius fuel economy.
That said: We drove 2,581 miles on 57.24 gallons of gasoline, for an average of 45.09 mpg.
Individual tank mpg varied from 35.56 mpg (when we had just got the car and were still getting used to it) to 52.33 mpg (highway driving on well maintained roads).
Cruising around Austin in an unladen car is a different story. I’m already learning to keep the mpg over 50 even on fairly short journeys, so hopefully we’ll do better in future.