When I drive the Fit, I get over 40 mpg as long as it is not really cold. I get right at 40 mpg when I drive it in the city, and 44-45 on the highway. In an equal car, I still get better, and more consistent mileage.
That said, the del Sol has better EPA ratings for both city and highway. She rarely drives the del Sol, and never drives the truck (I think the last time she drove it was when we test drove it). She probably put less than 250 miles on my 2008 Si.
I think that I do not drive much more conservatively than my wife. Rather, I drive more smoothly on the throttle and I do not slow down for corners as much. I also keep the car in gear when slowing for stoplights to take advantage of DFCO. My driving technique was honed in from 2 years with a Scangauge. I wish my OBD I del Sol could have one.