I want to finish what I started in this thread ...
The discussion is about my Vitz 2006 that is giving me 10 km/L within city with AC. A number of useful suggestions were given by members, but I did not have time to try them out except air filter change, engine tuning (from Toyota), gear oil change.
My concepts changed when I took the Vitz on the Motorway (Isb - Pesh) last weekend. I maintained a speed of 100 kph, and got a fabulous fuel average of 22 km/L, which is very satisfactory.
So, I guess the reason why I get 10 km/L in city is due to the fact that my regular use of the car is from my home to office, which are pretty close to each other. So, the car remains in low gear ratios, and gives a low fuel average. The car is perfect (al hamdolillah) and does not need any adjustments.
I guess its good news for Vitz owners !