Depends on a few factors:
1- Our fuel quality is pure rubbish, you might as well as feed diesel to the car
2- You NEED to mix Hi-Octane with each fill up because our Hi-Octane is about as good as the "regular fuel" this car is actually designed to run on.
3- The kinds of mileage I've noticed are like this (my car has 17" rims so mileage has suffered obviously):
8km/l in Karachi traffic; on Caltex or PSO fuel
9km/l in Karachi traffic; on Shell's fuel
10.5km/l in Karachi traffic; on Total's fuel
Thats with a 15 liter mix of Hi-Octane with each fill up. It all depends on how you drive, I've gotten as much as 450 KM per tank (with LOTS of fuel left to spare, but I fill up before the gauge goes near empty) within the city with uncle-ish driving and a consistent gear, and not using the brake needlessly. But I cannot force myself to drive like that for the heck of mileage lol.
Driving style is a very big part of mileage, with our other Civics, my dad always gets a better mileage, like 12km/l within the city (really); on the same cars I don't get above the same figures I've posted above.