It seems that the fuel consumption isn't correctly synchronized on multiplayer (at least on dedicated servers).
You can easily reproduce it by joining an MP game and you can see that on vehicles in which in singleplayer the fuel consumption is shown on the in-cab monitors, here is 0.0 l/h or even not shown.
Single Player:
Multy Player:
I found this issue on PC on a game without mods.
[Known Issue] Fuel consumption sync issue on multiplayer (dedicated servers)
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