I posted this elsewhere, but thought I should add to this thread as well ...
I have an SV6 manual sedan ... only have 1500 k's up,
First fill at 55k's, used std unleaded,
Next fill at 533k's, took 55.18l ... filled with Caltex Vortex
Next fill at 1114k's, took 63.95l ... filled with BP Ultimate
Almost due again ... with 1500+k's on the clock ...
So, from my calc, for consumption, I get ...
478k's from 55.18l = 11.5l per 100
581ks from 63.95l = 11.0l per 100
I have done manual calc's here, and suggest that is the only way to get an accurate reading. Do not rely solely on the trip computer ... it is only a guide, and remember to fully fill the tank so you know you are measuring from / to the same fill point each time (and don't rely on the fuel pump first click / 2nd click etc as they are all out) I fill mine to the top so I can see the fuel in neck of the fuel hose in the car.
If we can all keep a record and post details, we will get a better idea of the fuel consumption.
Sorry to be so anal, I am a bean counter after all !!