I reached 6.8L/100 KM after filling full tank in Bufallo (US), 87 Octan
Usualy I have 10-12L/KM, and I fill in Canada.
Car is Grand Caravan 2012, 3.6L engine.
This is unreal MPG for this car, how to explain.
I have a video with more detail information here
To add to Dragflaig's statement; everyone would be advised that, even if the computer is accurate, an mpg achievement at one particular drive period (either average or instantaneous) in one particular direction, especially during one particular tank of gas, is not an indication of real-world mpg for that vehicle. I've been measuring a long time, and it is not that big a deal to see some amazing numbers at times, but I pay little attention to an mpg average over just one short period, in mostly one direction.
For instance; I could fill up in Crossville, TN driving east with a normal wind coming from the south west; drive the rest of the way along the Appalachian Plateau, and then down into the ridge and valley terrain region to Knoxille, TN and would on an average day, achieve at least 15% better mpg that I'm going to get in that vehicle on a long-term average basis no matter the driving style or brand of gasoline, and certainly the octane would not affect one way or the other, except maybe my Ecoboost engine that actually produces more hp with premium.
The moral is that you have to let these things average out and there will be anomalies both positive and negative in certain situations and weather conditions, driving a certain direction. I wouldn't get too excited.