___A few things. Check that your tire pressures are at least pressed up to the level stated in the doors. This is way to low by the way. Secondly, since you have a NAVI equipped AH, head out onto a relatively flat highway, get up to 60 mph, reset your TC, and record the reading after 1 mile. While VCM is evoked (it will be at anything under 60 mph), you should see the iFCD pushing into the 45 - 50 mpg range and your final tally in excess of 45 mpg. The AH is a gas sucking pig around town unfortunately as its V6 while accelerating cannot be overcome w/ AS so that is out. Above 70 mph, VCM is unreliable so expect std. V6 like FE once you are pushing to higher highway speeds. I have never been in a hybrid automobile where the owner was complaining about poor FE and not seen the numbers pick up to the stupid level in a matter of minutes. There is that much of a difference between drivers unfortunately. Not that there may not be a problem with your AH but CRs received in the mid-teens in an AH on their city cycle w/ a 25 mpg overall rating.
___As for what an AH is capable of, I had one for less then a week 2 years ago and she showed me some darn decent summer time FE. Not quite as good as what I can pull from the I4 but damn nice with a little less then the kitchen sink thrown at her.
___And now the kick in the butt portion of this post If you need 250 + HP to drive around the communities you do, I have to wonder why you are even asking about having a problem with FE? The first place you should be looking for a problem is in the mirror I am sure your past automobiles what ever they may have been have all received their EPA ratings while driving at 80 + mph and then hard on the brakes down to 0 at each and every off ramp to a light or traffic jam ahead besides any light or sign while rocketing from stop light to stop light in any of the communities you commute through daily ...