Right - and I'm saying that playing like that is a fantasy of its own kind. I can see the attraction of it (and I do it myself quite a bit), but it's just as much a fantasy as the alt-history stuff is, because I know when I do it that the alt-history stuff definitely isn't going to happen.
This demand is somewhat specious, since I'm completely sure that no-one has done an academic study of the "IC effectiveness" of armoured cars in counter-insurgency operations, but I base the claim (which I stand by) on two strands of argument:
1) Counter insurgency had been known going back to the Romans' actions against gallic tribes at least. The keys to asymmetric warfare were well understood as networks of fortified bases combined with fast moving forces with concentrated firepower able to respond to intelligence about good rebel targets and swiftly relieve fortified posts under attack. Armoured cars fit the criteria for this force particularly well, being fast over and suited to using public roads (ie they don't chew up the roads they use) and capable of carrying heavy 'soft' firepower (MGs and light canon). They can also be used for pushing aside roadblocks and the like, where unarmoured trucks would be too vulnerable to be useful.
2) Armoured cars were widely used during the 20s, 30s and 40s by police forces and army units for counter insurgency work by forces that had a long history of such operations such as the British Indian and British armies, the KNIL, French colonial forces and home police forces, Italian colonial forces and US forces in Latin America. Given that these forces generally knew what they were about, it seems reasonable to assume that they specifically sought to acquire armoured car units for a reason.
Armoured cars of many sorts - including improvised and rather jerry-built ones built in very small numbers that it probably isn't worth specifically including in the game - were used in riot control, roadblock busting, rapid response and ambush, facility perimeter guard and road convoy escort in countless places around the world because they were well suited to the roles. None of the regular stats of the equipment (SA, HA, Def etc.) model this at all, so the inclusion of an (abstract!) bonus to supression seems reasonable as a way to represent it.
Just about all of the equipment and personnel used in insurgency supression and garrison duty were older, second line and/or lighter than those used on the front line. This was not a phenomenon confined to armoured cars, and the reason was simple: insurgent forces tended to be lightly equipped and few in number.
Your problem trying to rationalise armoured cars as something special is that it was somehow "important" for suppression is that population control is NOT about military force in that regard most of the time. It is mostly about manpower.... sure if you could issue an APC for every squad to make them more powerful and protected it would obviously help... but it is still the manpower that is necessary not the vehicle in and of itself... you can't just replace the IC used for deploying say 10 armoured cars instead of 500 soldiers and staff members.
This is why it makes no sense to go that route in the game... there are no relationship between the man with the gun and the vehicle and in which proportion the number of armoured vehicle actually is useful.
99% of suppression work is about information gathering and things that don't involve direct military threat... an armoured car is completely useless fort that. The armoured vehicle is only very useful in some specific situation while manpower is the most driving force of having a presence everywhere.
I would argue that an armoured APC or half-track wold make more sense than an armoured car if your argumentation was to be followed. Haf-tracks should have an even better suppression vale then.
The problem is that these assets was just way to expensive given the vast areas that need patrolling in WW2... armoured cars was issued to police forces as they were too old and outdated to perform other duties in combat formations, they did very well acting against lightly armed partisans and as general crowd control devices, no surprise there. Half-tracks were simply too valuable to be wasted in such efforts in any great numbers.
In my opinion the truck, car or motorcycle were far more valuable as tools in WW2 as they offered great mobility to way more people for far less cost. Mobility and the capability to quickly respond over a greater area was way more important than having a few armoured cars.
Armoured cars was a situational useful tool... but that was it, they did not in any way replace or augment manpower more than say trucks, cars or motorbikes Perhaps in a different way but that is it.
I would really like to see how many armoured car "companies" that was deployed for partisan duties during WW2... I would be surprised if there were many at all... these vehicles probably were distributed unevenly and situationally where mostly needed, not as coherent fighting units.
On the other hand... armoured cars was a very important part of army divisions. The vast majority of all armoured cars was working with actual fighting armed formations, not used as police forces... that was generally older less capable versions.
The problem is that the game is poor at modelling the importance of different types of equipment, the number of values needed to be modelled are too few for that. This is also why vanilla HoI4 effective divisions look very little like real life divisions.
The game is all about IC efficiency and making armoured cars so efficient that you include them in every garrison unit is not historically accurate, they were not issued in that capacity in any significant numbers. No one built armoured cars specifically for that purpose during the war. The only reason they were more efficient in suppression was their cost to operate and build per vehicle against say a tank.
