I had a 1998 registered city in pretty good condition. i think 1997 is the same model. fuel tank was 42 liters i think, average was 8-9 in city and ~20 on motorway to lahore (i know the difference between in city and motorway milage is way different than normal, but what can i say) same with CNG ~120KM in city in one tank and then on long route i used to go to sialkot from islamabad on one CNG tank (used to go there every week for job) and then use it for the day, getting refueled next morning.
but current milage of such an old car could be very different based on how well it was maintained...i think...