Ok guys, here goes.
After careful analysis, I can confirm that the automatic Suzuki Alto run at a preferred speed of around 65-70 kms per hour with an average weight of 2 to 3 passengers at a time gives you about 17.5 kms without AC and around 16 kms with AC. This is when the car is run locally within the city. I have not run it on a long route yet. The city is Islamabad with better roads and less traffic, so the average in Lahore or Karachi would be less.
The reason I replied this late was that I wanted to run this over a few times before I can post a final message.