Well, no idea about petrol, i only use petrol occasionally.
CNG with AC 110 km / (Rs. 500/Rs. 67.5) is what i am getting with AC on . City drive, 60Km running daily. sometime i drive madly and sometime i drive tension free (i.e. 2nd row which in 90% cases, car driving in 2nd row overtake the fast track at sh. faisal :P).