Think about this idea, as if enemy crew decided to dismount and abandon vehicle because it has lost combat capability. When dealing a final blow to a unit it will go a little bit off the road (to avoid unit clutter) and after short period of time vehicle will be considered "abandoned" and turn neutral to each side
Player that "disabled" a unit will get reward as usually, but destroying neutral unit wont give anyone any reward for doing so
Chance of this happening can be tweaked via mission settings or completely turned off. Base chance is also affected by damage that has been dealt, so for example if tank was taken out by AGM-48, its more likely that it will be abandoned than if it was taken out with AGM-68, and zero chance if it will be a cruise missile or a nuke
What it will give to gameplay
I propose a bit of change for APC's to make them more viable to use, that they would be able to carry engineering team and spare crewmen, that could capture those abandoned units
So, if APC would stay idle near abandoned unit, it will start to "capturing" it, progress will vary depending on type of unit (MBT will take longer time to capture than LCV) and its damage (if unit got heavy damage prior to destruction, for example if turret on top of MBT was taken out. Munition power and a bit of randomness will be taken into account too)
Logistic players that would try to "scavenge" unit on the battlefield will be rewarded for capturing each unit, while there should be a restriction for one APC, how many units it can "repair" and "restore"
Or, alternatively option for transport aircrafts to load crewmen and engineers to be able to capture units by yourself, but same rules will apply (need to stay idle, limited amount of "uses")
If pilots and crewmen someday will be limited, that can make some interesting interaction in escalation game where it would be crucial to save units and resources (men) in prolonged battles while also be able to capture enemy units