It depends on a lot of factors.
In Malaysia, we tend to speed, and speeds above 100 are very bad for FC. Of course, driving too slowly is unacceptable of course. Keep around 120km/h and you should be around the 13-14km/l mark, from my personal experience.
How many people and luggage are you carrying? Dun expect to have good FC is you ferry 5 people with full luggage.
In Singapore, we normally don't do that, so FC should be better.