Brother it should run atleast 120 in city driving..should go upto 150 minimum on long routes (considering 50L cylinder).
Get ur vehicle tuned up properly.adjust timing with timing gun.clean air filter.chck spark plug gap.If it doesnt help then go for cng cylinder + kit cleaning
i've got it tuned up and got air filter replaced and also replaced spark plug but it didn't help much. how much would it cost cleaning cng clinder + kit? and brother do you know any good workshop who can do this satisfatorily? this car is very heavy on my pocket.