I made an alternate Vossenack, where some Vehicles are almost never unused, even if under Shelter.
I can't recall the changes I made, but as soon as I return to default setup, they act as non-interesting to bots and that surplus to 70% of the inventory.
I was simply cloning some of the spawnboxes, on others I gave them new Boxes, the mix of
both made it. My version has no unused Vehicle, though it is a Tank frenzy. Main problem on Vossenack for Bots in Vehicles, is everything East of Church area, the objects are good enough for Human to drive trhough with a Vehicle, but for Bots this area is a messy adventure, they stuck at literally every object placed a bit on the streets. Ever wondered why the rush-out on Vossenack Axis Main is stuck before the wooden fence, it is one of this Wooden fence objects possibly seen as unpassable. When trying to drive trough you actually sense some object you pass, not like the other passable fence objects.
In notepad I've seen that this fenceobject is littered all across the Map and the reason for some areas not passable for Bots, although Navmeshed, as they want to pass.
I tried 2 version removing them completely, or changing with passable fences. Returning to stock layout I can't pass one of this section though, my tank just slides upwards on that fence. It is the vertical object of that fence part that remains unpassable/solid and causing laggs.
By removing that fence object, the Map has a 50% rush, that you can enjoy playing. The consolidated Vehicles spawns are surplus additions to the default very slow going Map.
They get trapped before entering neat points, Axis at entrance, where the Anti-Tank barrier resides, you can free this area from litter, 3 up to 5 vehicles still stuck, sth. initially slowing down the push of the Map, so I think it is some sort of neat point of Vehicle Navmesh causing culprit. To really get hell-of a tanking Map, it needs to get rid of such tiny hangers, more Bot-friendly Navmesh, but that calls for less litter in Church area and really closer look at all objects and make them passable, luckily this Map didn't need much overhaul, just a bit consolidation.
Apart from that it is a careless Map, I can only recall one major thing that needed overhaul, the 88 on that hill trench.
needs some lifting, as the bushes/vegetation cover the gunsight aiming, I put her on an
palette object slightly lifted, now the gunsight is free and good to use.