Just noticed that the smart has broken into the top 10 cars on Fuelly (
Fuelly | Share and Compare Your MPG). If you haven't signed up yet, go for it!
I was also using Fuelly to play around with some MPG comparisons between different makes/models. Take these numbers with a grain of salt, but at least they are based on real world numbers (as reported by owners) across all conditions. The average MPG for 2008 and 2009 model years rounded to the nearest tenth (exceptions/deviations noted for each model):
Toyota Prius: 44.1 MPG
smart fortwo: 38.1 MPG
VW Jetta TDI (2009 only): 36.9 MPG
Geo Metro (all available years): 36.7 MPG
Toyota Yaris: 35.9 MPG
Scion xD: 32.6 MPG
Mini Cooper (non S, 2008 only): 32.5 MPG
Honda Fit: 32.3 MPG
Hyundai Accent (2008 only): 30.4 MPG
Honda Civic (gas only): 30.0 MPG
Toyota Corolla: 30.0 MPG
Nissan Versa: 27.7 MPG
Actually, I wish Fuelly would run these types of averages for a given make, model, year, etc. so you could see where you stand in regard to the average for your vehicle.