So far, I am
So far, I am getting 41-42 mpg in mixed driving (lots of stop and go), which is exactly what my 2004 was delivering when I traded it in. I haven't taken it on a highway trip yet, but plan to this weekend. But let me tell you, the difference is night and day. I'm not really trying all that hard to get 41 mpg, whereas before, I was resorting to extreme measures just to get 37. I fully expect to get 45+ on the highway this weekend without much effort.
The biggest improvement is by far, the reliable IMA. The car is no longer unsafe, and delivers responsive and prolonged electric assist, with healthy battery regeneration cycles and reliable auto-stop.
When I first bought my 2004 Civic Hybrid, I was getting mid-30's on the first couple tanks of gas until I "learned" to drive it in a way that extracted max mpg. IMA vehicles are finicky that way; where the Prius returns circa 50 mpg without too much work from the driver, the Civic Hybrid is another story. First thing I did was toggle to the MPG indicator [0---20----40----60-----120] on the dash cluster so I could see it all the time and gauge my driving habits. Then I made it my mission to keep it in that sweet spot between "40-60" as much as possible, which actually wasnt that hard. The MPGs kept climbing, and soon I was getting 49.5, and then my highest was 53.3 mpg. After that, the lowest I got was during a very cold winter (39 mpg). They do not like the extreme cold or heat. But even so, 39 mpg in sub zero temps is nothing to complain about!
My GF had the same experience with her Insight when she bought it. She had no clue how to drive an IMA car optimally; she was coming from a V6 SUV and was not used to having to be so 'aware' of her driving habits. Luckily for her, the learning curve was much less steep since I coached her ;-) Now, she sends me pics of her mpg counter saying 48 mpg.