Just wanted to give a real quick MPG report. I got my car last week and have already driven it 800 miles. 75% city. I filled with 100% gas in St George UT. It was $4.00 a gallon, but I figured I would experiment a little. , and drove 128 miles back to my home in Las Vegas. At an average speed of 60MPH, I achieved 56MPG. I kept it on cruise for a majority of the time, and did draft behind a few big rigs. Based on the current MPG, this car isn't costing me a dime since my old car was getting only 25 MPG. I will post additional impressions of the car as I continue to drive.
Good experiment and welcome to Prius Chat! I am experimenting too but I have a hard time getting outside of the eastern corridor reformulated gasoline region, so its slim pickens for me. Maybe I get west to Pittsburgh soon...and break the confines.