Not very many people in the forum seem to be interested in the potential economic mechanics of this game, which I don’t quite get.
As for your idea, I would want the option to have an automated system to buy and load the fuel for me (ie: auto buy x quantity of fuel below a certain price level). For me, having to make sure each train is fueled would be too tedious/micro managing for me. I like this idea from a commodity/business production perspective.