In DAS Developer mode :
Koiinstrument -> Diagnose
Steuergerate-Anpassungen (Variantencoderierung) -> Variantkodierung Werkeinstellungen ->
In the menu that
enable this option
now you have
If you
you scroll a little more down
you can change it from L/100km into km/l
Scroll down and confirm Coding by pressingF3
if you watch your Instrument
For
to do this in Developer mode we go back by hitting F1 -> 3 times
then choose Ansteuerungen -> Gesamstliste
Scroll down
Press F3 and confirm again with F3
Now you will see the "Koiinstrument" reboots