The E6B is a mechanical, hand-held, device. It would take a very, very specific hit to take it out. If you lost your fuel gauge, it would be harder to use the E6B to make the calculations.
Maybe some real pilots could sound off on this, and we could learn something about fuel and distance calculations.
Good question Mongoose, but there are so many variables in real life, which are not included in this game, it would almost be impossible to be accurate! Fuel flow management for example, there are no "fuel mixture" controls on any of these a/c in the game!
but, to maybe add to the discussion; first, how much fuel do I have on board? second, how far can I go on the fuel I have? third, what is the distance to where I need to go! forth, what is my ground speed? The true a/s in this game only gives you the "standard" atmosphere ingredients, 29.92 barometric pressure, 59 degrees temperature, with zero wind! Of course those are based on "sea level" conditions, not conditions at say, 10,000 feet. Of course you could use the standard temperature lapse to 10K, 3.5 degrees per thousand feet, but do I have a tail wind, a head wind or wind from any direction which would affect the amount of time you have aloft. Do you have a "high time " engine, which usually has a higher burn rate than one of low time. Now, you throw in the changing weather conditions, i.e., flying from low pressure area to high pressure area, change in temperature, now the increased airspeed because of weight reduction because of fuel burn!
As you can see, it is a very difficult task to do as you ask! As in real life, all the above are based on "estimates" and what actually happens is usually two different values!
When I use to "ferry" bought and sold, used aircraft, I had a rule: 1 hour reserve, plus 45 minutes, unless it was a single engine light aircraft, which it really was never a problem. The problem came with heavy multi engine aircraft in instrument flight conditions, then you have to be able to come up with some kind of estimate or bend over and kiss your A++ goodbye!