Great car. Small cross sectional area, lower Cd than the hatch (.32 vs .34), taller gearing, and a "larger" 4 cylinder engine (1.3 L). Suzi does great and has consistently returned me 50 mpg in the summer if I try. I have done some aerodynamic modifications to her, so I really need to do some new measurements to get new Cd numbers. I recently crossed the state of Illinois (north to south) on a single tank of gas and without stopping. Average speed of 61.7 mph, and average fuel economy of 48.4 mpg. If I had my instrumentation working, I would have set my sights on 50 mpg, and let the speed fall where it may.
EDIT:
I had done a coast down test once before the aero mods(single coast down in a single direction) and determined my Cd,Crr to be 0.304,0.0147. On my trip to Wisconsin (where I got the 48.4mpg@61.7mph) I did another coast down, again single coast down in a single direction. This time the Cd,Crr come out to be 0.265,0.160. I know the results are not rock solid, but even if it's close, the mods are a HUGE improvement. It puts me close to the Cd of my wife's "new" Prius II!
EDIT:
I did a real coast down test, 5 bi-directional runs in great conditions. The results showed Cd,Crr = 0.28,0.12. This is about what I had expected due to the inaccuracy of the original coast down experiment without aeromods. This is about 14% less drag than stock, with $0.00 invested (used campaign signs were free!). This should result in about a 7% increase in FE.