The road from home to Timonium: North on Connecticut, East on the Beltway, North on 29, East on I-70, North on 695, North two exists on I-83. Approximate distance is 50 miles.
Driving to Timonium this morning, I decided to be the perfect Prius driver, nursing my car along in such a way as to maximize gas mileage. To my surprise, when I left I-83, I had averaged 56.5 miles per gallon.
Coming home, I decided to drive normally, not worry about too much acceleration up the hills, passing cars when I wanted to, exceeding the 55 and 65 mph limits in my normal manner. When I arrived him, and looked at the mpg-o-meter, I saw I was at 48.7.
Although 48.7 is quite good (obviously), there is quite a difference between that and 56.5.