I'm in Sofia (Bulgaria), and I've filled up in Poland and drove here 1211km for now. I was doing my best to perfect my target driving, with my newly calibrated and updated MPGuino (thanks t_vago!).
The numbers I got was just amazing. I've finished my trip here with FE of 3.47 l/100km (67.79MPG US).
So I've broke my personal best. Havent filled Berta up yet so that's not confirmed yet but fuel gauge is showing lots of fuel left.
So that's quite possible that the numbers are right. I'll post more after filling up Berta's tank.