My Alto stays home with my wife and mother at home small drives it doesn't 15/16 kmpl
If I take it to office defence to Site it manages 17.5 to 18 kmpl in stop and go traffic ( 2 patches signal free around 5/5 kilometers.
I doubt if this car would do any better without ac the AC puts very less load on the engine.
If driven constantly on 80-100 on a motorway it would manage 21/23 kmpl.