P.S. I own Chevy Aveo 1.4 A/T. In the city my petrol consumption is 7km/ltr(Extremely bad traffic in Bangkok, Thailand) and 16km/ltr outside the city. Never convert to MPG, so you might have to do your own conversion.
I'm in Bangkok also, driving, what sounds like the same vehicle as you in similar conditions.
But I have to add that I've never had fuel consumption as good, or bad as what you've mentioned. In town I get around 8.5-9 and on the open road, maybe 12 ish.