I bought my 2012 LX last Saturday with 8400 miles on it. The odometer and MPG had never been reset. The 23.8 MPG had me a little worried but the previous owner put less than 3000 miles on it per year and probably never drove on the highway. It looked at the CARFAX before buying it. The dealer did only the second oil change on it in 3 years. The previous oil change was 3500 miles and 13 months earlier. The first oil change was done when the car was nearly 2 years old.
Anyway, for the first week I've owned it I'm at 30.1 MPG in mixed driving. And it's slowly still going up every day. I have the ECON button always on and use the cruise control on the highway. The 1998 Civic DX that this replaced averaged 28-29 during the winter and 35-36 in the summer. So I expect this car to do slightly better with ECON on, impressive since the 98 Civic has a 1.6L engine.