My inter-city mileage is 16-17 km/ltr (Eco OFF) , so i guess your mileage is fine.
21.3 km/ltr i acheived while going on highway (60% city drive, 40%Highway drive) with AC on going one way. It was a 120 km trip.
Tips that might help (hypermilling works)..
Turn Eco OFF, it chokes your car.
Fill your tank with a 70:30 Petrol:HOBC mix.
Engine oil 5w30 (I use liqui moly)
Check air filter regularly (Try using leppon, its cheap and very good. Rs.400 as compared to Rs.1500 original. I change it every 2 months even though its "clean")
Regularly monitor tyre pressure (once a month is enough) I maintain 28psi in my OEM tyre size 165/70/14
Drive with windows closed and AC on when on open roads, reduces air drag.
Learn to manage your acceleration pedal. Heavy foot causes loss in power, more fuel loss, nd sluggish acceleration.
Try not to use brakes alot, keep your eyes open and drive intelligently.
Try and fill up your car in the early hours of the morning (like fajar) as the fuel is cleaner then due to lesser turbulence in tank.
Hope it helps bro