Its Liana 2008
Liana 2008 , on CNG it gives approximately 14.5 KM / KG and on petrol it gives 12.5 KM approximately / Litre at average speed driving...
At slow traffic it will be approximately 11 KM / KG CNG and will be approximately 9 KM / litre petrol
Involvement of these matters
1. Air in tyres
2. Air filter cleanliness
3. Engine oil cleanliness
4. Plugs cleanliness
5. CNG quality and pressure
6. Petrol quality
7. Throttle body cleanliness
I think your car will definitely give you best mileage