Try getting some highway driving as well to observe your FC. The case with my Altis, i average between 9.5 to 10.5km/L in city driving, the same as my gasoline figures however in highway driving, i'd get around 10.5 to 11.5km/L with LPG as against 13km/L to 16km/L with gasoline. When Xoom checked out my tuning, he saw that i was basically stoich in the low rpm range and running rich at the high rpm range so we would have to work on tuning that.