I think the first step you need to do is, calculate your FC accurately. Once you know the FC is accurate, then you can use that calculation to decide if you have a problem. I think manuals avg around 12+km/l.

Please use the following steps:-

1) Fill full tank.
2) Reset odometer.
3) Drive normally until it's time to refuel.
4) Refill full tank.
5) Make a note of how many liters it takes to refill full tank and how much mileage you travelled. This is what you will use to calculate FC.
6) Repeat steps 2 - 5 at least 3 times to get an avg. The more the better.
7) Always calculate in km/l, not cents/km because prices change, making your calculations obsolete.

Once you have an accurate reading of your mileage, then you can decide if you have a problem or not. Your previous readings did not follow this process and thus might be wrong.

http://www.fuelly.com/driver/eyezax/saga/log

Er... dude,

Firstly you must enter the data accurately. Either enter your odometer reading, or the reading from the trip meter (remember to reset it).

(I personally prefer odometer readings, because before I drive off from the pump I automatically write the details (date, odometer reading, quantity, fuel brand and octane) in my logbook, but sometimes I forget to reset the trip meter)

Secondly, you must fill until the tank is absolutely full. Read this to find out why.

Let the nozzle trip by itself, then squeeze the handle gently until the fuel almost overflows.

If you don't do these two, the results you get will be erm, inaccurate.

And what do you mean you can't remember?

PS I suspect you are entering your odometer readings but the input is set to Trip Miles (or km). Go to your car in the Garage and click on Edit This Car to change it.