And yet I regularly calculated the mpg on my CTX1300 Deluxe during the "normal" riding season at an average between 48-52 mpg... very consistently. Mine only dropped below 45 mpg when temps dropped below 45F. I rode mine at all temps from well below zeroF to near 100F. Hotter temps resulted in better mpg. I and my bikes don't pay much attention to factory claims for these kinds of details.
YMMV depending on how aggressive your right wrist happens to be. Lowest mpg I had (after initial break in miles) was 39, I think or possibly 37, but temp was at or below zeroF for that. Best mpg I had that I remember was about 61 mpg on a rather hot day in the mid/upper 90sF while on a trip riding all state and county highways.
Would be good to show a picture with the passenger backrest.