Questions: Do the fuel needs seem realistic, reasonable, balanced? Are there anyone who needs a new permanent fuel barrel (+1 fuel every turn) or any nations who need to get a fuel barrel removed from start?
My initial impression is that the total amount of fuel in contention is too low. Granted this is based purely on games played vs the AI, but I suspect the same would hold for head to head games between two or more human players.
Right now if you hit the zero point where you run totally dry, there's usually not enough of those oil drums in range to make up the gap during subsequent rounds. Sacrificing expensive units to free up fuel for movement during future turns is pretty counter intuitive, and in some cases might not be possible even if you wanted to, because here's no kill button to scrap units. I guess you can always crash aircraft into the sea, but if you want to get rid of mech or ships etc. it still requires a way to battle, and there might be no enemy units in range for that.
The question I keep returning to is whether the strategic interest created by hard fuel restrictions is overshadowing the more general sense of gameplay enjoyment? like if you hit the wall too soon with fuel, or if the options for recovery are too limited, then most of the game is reduced to units that can't move, which gets old pretty quickly. Similarly if you can't purchase new fuel consuming units and move them around, then a big part of the active game is kind of undermined/transformed into static defense purchasing (like where the heavy hitters just stay in place at the point where they spawn.) That sort of stuff heavily favors the defender over the attacker, and makes an already grinding infantry push dynamic that you see in traditional A&A even more grinding. E.g. A defender can spawn tanks and fighters without expending fuel, but the attacker might have to move such units 3-4 spaces sucking up a shit ton of fuel before they can even reach a target.
Just as an example, Germany has what like 30+ fuel consuming units and 55 starting fuel? Each of those units has a range of at least 2 spaces. This means that if Germany moves everything they can 2 spaces, then they are out of fuel before the first turn is completed. Germany's available fuel production at the outset is 30. The only real targets of opportunity on the first turn to expand that are Algeria, Norway and Normandy worth 1 fuel each. So basically 33 tops, if everything goes well. If they go full lightning war in round one, then Germany can maybe move half their fuel units the full 2 spaces in the second round, which is basically grinding to halt before the game is even underway.
Honestly I think the fuel could be doubled across the board, meaning everywhere there is currently 1 barrel, there should be 2 barrels. Players need some kind of fuel cushion to work with, one which will assume that they are going to purchase lots of new units (beyond their starting forces) and wanting to move them around, at least for a couple rounds.
For historical distribution of actual oil across the map, that is pretty tricky to model. I like the way you have it done here. I favor gameplay over realism there, and just saying that any historical/realism anomalies are due to stockpiling. My understanding is that in the period covered by this game most of the worlds oil was being produced in North and South America. I think it was something like 200 metric tons coming out of the US, Mexico, Venezuela etc. with the rest of the world combined producing less than 100. That would be too uneven to make for very interesting land grabs or oil rich territory trading. So I like the current spread, and the current locations (they all seem plausible). I just think the flat totals should be increased for everyone, to facilitate more movement and larger swings when those oil producing territories trade hands.
One other thing... its still hard to tell at a glance how much oil production a player actually controls versus how much fuel they have on hand. Since this is now the most important resource in the game (arguably more than PUs even) it would be nice if there were separate economy columns showing Fuel/Fuel Production, the way that PUs/Production are listed separately in the main stats window. I think something like that would make it easier for players to parse those screens when they are looking at the starting fuel reserves, versus what they can recoup per round.