Having several thousand hours in WWII era aircraft, I can tell you that fuel gauges of that era are not particularly reliable.
Sure some have fancy markings and such that might make you think you have a specific amount of fuel remaining but they cannot be relied upon.
The procedure was to fill the tank and look and make sure it was full OR physically measure the fuel with a graduated stick if the tank was partially full.
Once you start the engines, you track your power settings and time and make sure what you see on the gauges sort of jives with your planned fuel burns.
Colmbo can back me up on this.
What AH calls an E6B is a actually a very sophisticated fuel management computer that does what only modern aircraft do. It tells you exact fuel load, minutes and range at current power setting/speed. We have way too much information for WWII flying but thats okay.
We are missing some basic tools such as a distance measuring tool but its sorta easy to guesstimate range with grid squares.
What i would like to see is a player settable fuel light instead of a hard coded low fuel light but thats just me.