I would say that it depends on your longest tank and native units
In every case, as soon as you hit the kilo-kilometer, your goal is the kilo-miles
I reached 1825km (1134mi) lately, so my next goal is 2000km (1243mi).
Now some people have 45L (11.8 USgal) tanks, while others (as I do
) have 60L (15.9 USgal)...
While a kilo-miles with a 45L tank is 2.797L/100 (84.75USMPG), a kilo-kilometer with a 60L tank is 6L/100 (39.2USMPG).
POE (Pourcentage Over EPA, whoever is your "EPA") is a little bit more fair. I scored over +100%
but traffic and warm weather are back
Have fun at improving your PB,
Denis.