For those who want a better fuel supply system can i put this forward . Before a battle we get a supply of fuel sent to us by high command along with our prestige. Lets say 100 fuel and our Core units selected will use 100 fuel . We then have a choice to swap some of our motorized units out for wagon drawn , Heavy tanks swapped out for light or medium ones saving fuel . This way you get a better fuel system , i think , without the micro management of convoys. As the war goes on the fuel shortage starts to bite, so you must save fuel or run less mechanized units