So far we are really happy with the FE of the civic. My wife has been returning trips in the low 40s (according to scanguage) driving pretty much her normal ways. Last night she came home from her mom's with a 44 mpg trip and she was going 70 mph on the highway. It's nowhere near broke in with only a couple hundred miles, so I thought that was pretty decent .
I have been thinking of adding some of the hybrid civic aero mods to it to drop the Cd into the upper .20s .
Best tank= 81.23 mpg on july 1st 2008
SAVE SOME GAS, SAVE THE WORLD!