yes it should be improved more... i do on my city 1300cc 2005model manual 200Km in 450 CNG with AC last weak coming to Karachi from Lahore.
cng doesnt suit better to anything than a non vvti 2nz-fe
yes the guy isnt crazy.city idsi fetches this much outa cylinder.i had idsi thing same 20o5 model.and it never gave me less then 20okms/cyl in standard 55 cyl.