First of all, the normals you described are not correct.
In lahore, hustlers are usually giving between 19.5 - 20 without AC.
Mine is 2014, my normal load is two adults, and 2 children. My car gives me around 20.5-21.5 in city with AC. (I drive with a very very light foot).
Having said that, get your O2 sensors checked. it has two of them on the CAT. if they malfunction, the car runs lean and has significantly reduced Average. I suffered from this in 2021. reduced pick. low mileage.
Eventually, I got the Throttle body serviced, Got new plugs, and fuel filter changed. the problem was reduced to half. Then they did something to the O2 sensor. I think, the connection had fallen out or something.
right after that, the car became A ok.
try getting the O2 sensors checked.
