NzBeagle:

Fred99:

I've been driving two different make near new vehicles on the same route, similar traffic conditions, same load, driving normally (not trying for maximum fuel economy).

One has claimed combined economy of 8.2l/100km.  Actual has been 7.4 open road, 8.5 around town.  Claimed economy seems about right - at least nothing to complain about.
The other has claimed combined economy of 6.1.  Actual has been 7.5 open road, over 8 around town. It seems to be using at least 25% more than claimed.

Of course this is pretty meaningless, there could be other reasons, but if smells and looks like BS...

For myself, I've found the reported economy (dash) is about .2L/100km better than actual pumped fuel economy, which puts the car over it's advertised economy! Cheeky buggers.

You are Probably estimating fuel amounts within the errors of the filling pump. How do you know to fill to the exact tank level each time? You can't see inside the tank. But these should average out over a period.