Results of hypermiling so far...
 

I just bought a Fiat 500. As you can imagine, I drove it like a bat out of hell using the dealer's complementary first tank and it lasted about a week. Fuelly reported that I got 27mpg. So I switched to hypermiling and the results are 33mpg.

The engine is hardly broken in and hasn't hit 1000 miles yet.

27 to 33 seems ok, I wonder if I can do better? How much can the MPG improve over time? How long does it usually take for an engine to become more efficient?

drive gently, don't lug the engine

Check what others are doing here : Fiat 500 MPG - Actual MPG from 644 Fiat 500 owners

From my simple spindoctored mathematics, by the time the car your car is 47-years old it should be able to get up to 39.6mpg.

1970 Fiat 500 MPG - Actual MPG from 1 1970 Fiat 500 owners

Well, that's what the evidence suggests .. :rolleyes: just wait till the car is a bit older.

Don't expect the engine to get any more efficient than it already is.

I would disagree with this comment based on my experience.
I Bought my Rondo new, only new car I've ever bought. I bought a Scangauge right away, tried hypermiling it right from day one and I've tracked every ounce of fuel I've ever used. I know it took 4-5000 miles before I could even consistently get the EPA rated mileage and more than that before I was beating it. Give it some time and get yourself some type of mileage monitoring.