I honestly don't know, but in CMSF we have armored vehicles that fight pretty closely with the infantry and can resupply the troops very quickly. Is there a WWII equivalent? I know we gamers like to use halftracks as IFVs, but did they really get close enough to the shooting to be useful for quick resupply on a regular basis? Did they carry stores of ammo and equipment to be used by the infantry they carried? I can see where an offensive push would come to a halt and units would take time to send men to the rear for more ammo, but I've had the impression that the men pretty much carried all the ammo they were going to get for a day's fighting.
I'd love to see troops resupply because nothing in CMx1 would frustrate me more than to have my men run out of ammo halfway through a battle; I just don't know how realistic it is. BFCs response had always been to use your ammo judiciously.