Forgive me for saying it but if you're using 12-13 l/100km are you sure all is as it should be? Unless you're driving it like a racing car I would expect 8 or less, or in British terms 35+ mpg not the 24 or less you mentioned. I'd be looking for binding brakes - find somewhere quiet to roll to a stop without touching the brake pedal then carefully check if any of the wheel hubs feel hot. Also air filter and 8 plugs.
Thanks for mentioning it. Previously, I too was wondering before why my fuel economy is like that.
My daily usage currently is:
8.0 km going to destination, and 8.0 km going back home.
8.3 km going to destination, and 8.7 km going back home.
Other amenities (groceries, park, mall, clinic, church, restaurants, etc.) are within 5-10km of my home, so I seldom travel longer distances. The travel is also a bit start/stop because of roundabouts, school zones, and humps around the area. So I thought that the fuel economy is due to my daily routine.
Additionally:
1. I asked a mechanic (but not from the Honda service center) about it, and he said it is also due to my usage.
2. Early this year, before the pandemic struck, I had an opportunity to travel 76 km straight to a destination, and most of it was on an express way. So what I did was I reset the trip monitor from the dashboard to be able to ascertain what the fuel economy was in longer distances. At the end of the trip, the trip monitor showed 6.6L / km which is exactly what is advertised for my Honda Jazz variant (this is the brochure for reference on fuel consumption:
http://australiancar.reviews/_pdfs/Honda_Jazz_GE-I_Brochure_200902.pdf). So I assumed there was nothing wrong with it.
Do you guys think that even with this routine, the fuel economy on the Jazz should still be better than 12-13L / 100km? If yes, then I will have it investigated.