Any bumper-to-bumper traffic on your route? Do you keep the engine running (so the A/C can operate) while say, waiting for someone? These are just some of the fuel economy (FE) killers.
Anyway, by my computations, you're most likely doing anywhere between 3-3.5 km/L.
Almost 3/4 tank = ~35 liters
Almost empty = ~15 liters
Used fuel is 20 liters for 60 kilometers traveled = approx. 3 km/L
You can do a proper computation by doing a full tank (automatic shut-off at the pump) and resetting the trip odometer. Disregard at this point how much fuel was loaded in your car.
Use the car as you normally would until almost empty or when the fuel low light comes on. Fill it up again to full tank (automatic shut-off at the same pump). This time, note how much fuel was loaded and get the reading from the trip odometer. Use the following formula to find out the actual fuel consumption.
Trip odo reading in Km
--------------------- = Fuel consumption in km/L
Fuel pumped in Liters