We went from Ithaca, NY to Baltimore, MD and back.
In our Prius.
We went over mountains (OK, for you folks out west, hills - up to 1800 feet and back down, a couple of times each way).
We used the air conditioner and window defroster.
We drove part of the way over 70 mph (OK, I let my husband drive for two hours.). The rest of the way, between 63 and 69 mph.
We had three people in the car, and the hatch was filled with luggage.
It rained part of the way down, and most of the way back.


And we still averaged over 51 mpg.

WE are happy with our mileage.

 

Alot of my travels in Maryland takes me over these "big hills" and it kinda hurt my FE at first but now I have learned how to fight that and maintain over 50 MPG. Good Job!