After one of the longest sorties I've flown so far in the game, which took place last night, I can confirm that the Spit's fuel gauge does work.
It follows what a poster above said, re the top tank feeding the bottom tank. I didn't make a note of the duration of the sortie, but by the time I landed back at Manston, I was down to 25 gallons, having taken off with 100% fuel.
I also had a backside like a piece of lead, and was desperate for a cup of tea. Now that's realism!
