TL;DR
Cars and Tanks should have their own logistic slots like the player character to stay supplied with ammo / fuel.What ?
Cars and tanks which return to base could be automatically refueled and resupplied by logistic robots. Just need one new technology which provides a small set of logistic request slots to each vehicle.Why ?
A boring bit of the game is having to keep worrying about refueling your vehicles. I don't generally carry around a bunch of fuel, so if I forget to refuel, I can easily get stranded miles from anywhere, which sucks as gameplay. It seems like it would fit the theme of "automation" at the core of Factorio if you could set-and-forget your resupply, like you already can for trains.Whether or not this should apply to trains is debatable! I don't think they need it, but others may disagree.