yes agreed with you dear, by the way i have installed mehran carb, priviously my average was 9km/L in city, and vehicle gives black smoke,
but after installation of china carb (Laal box) for mehran, and change of spark plug with G-Power narrow pin, it achived 16km/L in mix drive, and black smoke vanished.
my engime was old, and head was welded.
my painter drive my car without turning on radiator fan and it get heatup during 40km drive, so it started reducing oil and give white smoke.
so i want to swap engine with fuel economy, as drive is with in city by my wife.