This all has to do with driving habits. My wife has a 2012 Mazda 3 Skyactiv which is rated at 39 mpg highway and she is getting anywhere from 29-32. This is all due to how one drives and the type of commute. Accelerate slower from a stop and you'll increase mpg. Also at 26.5 your wife is pretty near the average mpg rating of 28 so I'd say she's doing pretty well. We have never seen the 39 out of our 3 either but that is because we typically cruise between 70-80 on the highway on long trips which at most has netted us 35-36. And also a few posts back I posted about my 700 mile trip in my Saabaru. Driving at cruise at 65 I netted way better mileage than the vehicle is rated at. Ones foot plays a big role in mpg and the more cognizant you are of it the better mpg you'll get.
Regarding the XV yes they are virtually the same and I know this. But who cares what they call it really? It is cool for what it is and in my opinion from an exterior standpoint is better looking than the Impreza. It's just a name and I have a feeling the XV is going to sell very well. So well that the Impreza Sport will probably disappear.