Now it's about 2+ months I started driving my Mira 2006 Model and Manual. Initially was way disappointed due to its unexpectedly low mileage of 11 km/l, as fuel economy was the main attraction for buying a 660 cc. Tuning of car didn't do any good. Later, however, I realized if I re-fill from a good reputed pump and preferably keeping same brand (Shell in my case)... mileage increased up to ~ 14 (50% time AC+shitty traffic of Karachi).
I believe the idea of Mileage is a complicated given its dependence on many factors - road roughness, traffic, fuel quality, heavy rims and tyres, driving habits (like driving at unsuitable gear or rapid race in automatic) - in general any thing that requires engine to exert more. Hence, the average will vary. I have heard that the claim of mileage made by a company is always based on ideal conditions performed in a lab. It, therefore, obviously can't replicate conditions in practice of any country in general and Pakistan in particular- I'm sure Diahatsu people can't even imagine how things are in Karachi.
Nevertheless, coming back to my Manual Mira 2006 model, I'm quite satisfied as I don't see a better option in Pakistan for the price I gave (~ 7 lac). For local manufacturers I could get new Mehran, Coure & Cultus. But Mira proved better for its impressive pick-up, AC performance, spaciousness etc. Currently, it's giving 13-15 km/L.
So, as a beginner my suggestion on mileage is: Don't be too quick to reach a conclusion based on initial observations. Keep noticing things and while making a comparison do take into account aforementioned conditions.