Permit me to add. As you can see many here are stating CX5 is living up to expectations in terms of EPA. It's obvious you have done your part in trying to bring up the mpg. Folks questioned your driving habits but apparently you had other cars where you drove like today and it met the published EPA.
The only thing maybe then is the car? Did you consider going to the dealer and have it evaluated for any issues? Like some ECU stuff missing or I don't know? You might scrape thru within the power rain warranty by carefully wording the issue to the dealer.
I honestly don't think anything is wrong with the vehicle. It runs smooth, no SES lights, and everything "checks out" when I look at it. I did a 0-60 test and it was right where it should be at around 7.8 seconds. Often, if a vehicle is down on power, it's not running efficiently at any other acceleration parameter, either, hence I mention it.
I really think it's just the weed-whacker 4 cylinder + wind drag. All my other vehicles have been somewhat powerful, and I think that the 4 cylinder is far outside of its element at cruising speeds, and gets "loaded up" quite a bit more, percentage-wise. (I would need a BSFC/load chart to actually put money on this theory, but I had BSFC charts for some of my other vehicles, and 80mph or so was their sweet-spot, rpm/BSFC wise.)
Part of the pitfalls of a tiny motor in a high-demand (SUV at speed) application. That said, doing city-speeds, it pays for itself, while my other vehicles were in the mid/high teens, this is in the low 20's.
Regardless, the vehicle delivers 100% as it should, except in the mpg department for how I drive. I did hypermile it once, and it did actually exceed sticker, so I don't think anything is "WRONG" with the vehicle. I just think that it's a far less capable ride than I'm used to, and it can't soak up the extra demand I place on it as effortlessly as my other cars and SUV were able to.
Chalk it up to trade-offs. Granny and small-staters with their slow speed limits/driving habits are going to get sticker, probably. Us southern boys with out 75-85mph speed limits are going to be frustrated. Can't please everyone, and more granny's and smallstaters buy CX-5's, so...