I will give a bit more info on mine.
My last few tanks:
11.7
12.4
12
12.4
12.5
The slightly larger tyres make a good 1L/100 difference. Plus I have bull bar, winch, full length steel roof rack. Often have things on the roof rack and decent weight in vehicle. I can easily see people getting 10L/100 if you have a completely stock vehicle. That's the difference.

