Not over the whole tank, just GC to Brisbane. The trip I did involved about 100kms and the ambient temperature was about 30 degrees which was also interesting.

Previously I've done Brisbane to Hervey Bay return and got 6.8l/100km with the air-conditioning on the whole way. That trip also included some fun winding bends and hills between Kingaroy and Maryborough at 80-100km/hr. I refilled the tank at 730kms.

What I'm saying is that the conditions you drive in play a massive part in consumption. I have read comments on this forum of people who claim the difference just in air-con on or off is up to 1l/100km. Now the trip I did from GC to Brisbane is basically ideal conditions so by my calculations its entirely plausible to repeat this kind of consumption.

When I get the chance I will hopefully be able to repeat the test and will let you know how I go.