I just got a Mira 2008 Automatic. I have driven it for almost 15 days now and on full tank it's giving me 17-18 km/liter. A/C is mostly switched off but on when driving with family. Without A/C my guess is it will give 18-19 km/liter. My drive is mostly in heavy traffic, going to office from Rwp to Isl daily and coming back in rush hours, and going to sadar etc on weekends with family. On long I'm sure it will easily give around 20 km/liter.
I changed oil, oil filter, air filter and plugs immediately after buying. I didn't get the catalytic converter removed. After 2 weeks I also had to change the battery. I guess the trick is to drive on light foot, and keep the maximum speed up to 80 km/hr. My speed is mostly between 50-60 km/hr due to heavy traffic. I am using Caltex Premium Petrol from F-6 Islamabad. Also tried Total and Shell, but I think Caltex is somewhat better.