welll I own city 2002 exis and literally, i enjoy its consumption. On long drive, it has always given me 16 Km/L while in city its around 10-12 Km/L.
While on CNG, its around 175 Km per Cylinder if pressure is around 240 KBar.
Now coming to point, reasons of low consumption. there are several factors associated.
- Spark Plug
2, Air Filter
- Engine oil
- Fuel filter
- injectors..
Last but not least. Jitne chwl mechanics hote hain.. you wont find any ghatia people thn that.. Real mechanic u have to find via big struggle. I bought city from known person.and uptil this date sing July 2014, I havent done any major work of engine. THese spark plug changes, and oil change are periodic matter to change so its matter of maintanence.
3 months back, my car average on Cng was reduced to 120 to 130. I replaced spark plug and did Carb cleaner spray in the Aircleaner beneath injector area and my car efficiency regained with enormous feel of thrust.
I hope this works with u