Is the fuel consumption for the 2009 Liana 1.6 automatic reaching 10 liters per 100 kilometers because of a faulty oxygen sensor or carbon canister purge valve? I've checked the spark plugs and ignition coil, and there are no issues. Any advice from the experts?

Excessive carbon buildup!!! Last month, when I went back to my hometown, the mechanic asked me to add a can of carbon cleaner. Then I drove back on the highway and continued with my daily commute, and the fuel economy improved! You might want to try it; mine is also an 08 automatic.

This issue might be causing it. If there's a problem with the oxygen sensor, it could lead to high fuel consumption. I suggest getting it checked out and maybe clean the carbon deposits as well.