Slightly off topic and may not be linked, but over southern France today I heard a Ryanair aircraft ask for a more direct routing as they were quote"running low on gas". My colleague and I couldn't believe our ears!
I work on TWR at an aerodrome with typical taxi time of 10 minutes. On occasions (bad wx with runway changes, twy closures etc), with that time extended, I had several a/c from different airlines (RYR has only one flight here) asking for priority in departure sequence because they're running low on fuel. One German crew when asked to expedite their backtrack due to an a/c on final reported unable due to running on one engine to save fuel. Of course no previous mentioning of shutting down the other one...