Issue description
When supplying a factory or other kind of non-storage destination directly, it's very common to bring materials in small batches (often 20), even if the truck supports a larger size.
This is a particular problem in the early to midgame, where the player first encounters capacity-60 trucks. They seem like a drop-in replacement for capacity-20 trucks, so the player naturally builds some, only to find that many of the trucks still only carry 20 at a time, even if partial loading of trucks is disabled. This leads to a dramatic waste of fuel and a big fuel crunch that may come as a surprise when the player thought they were doing an upgrade. At this point in the game, I was still relying heavily on trucks for directly loading factories (as opposed to belts), so it hit me particularly hard.
Expected behavior
I think I understand why trucks use undersized loads when supplying factories, so I think I understand why that can't be "fixed". But there are ways this situation can be improved on.
At the very least, this pitfall should be documented. It took me quite some time struggling with fuel problems before I realized what was going on here and it was pretty frustrating, so it would've been nice to know beforehand that even though the trucks have 60 capacity, they often won't actually use it. I could have taken precautionary measures, for example using them as mining trucks only.
The AI should bias in favor of picking small trucks when assigning small pickup jobs. Currently it seems to pick randomly, but it would be much less punishing if it used the capacity-20 trucks for the small jobs and capacity-60 ones for the bigger ones automatically. This is the behavior I would logically expect, and it would reward the use of a mix of both truck types.
Game version
v0.4.8