As it is, armored cars don't really have a reason for existence. If you want a garrison, you might as well make cheap light tanks. If you want light tanks for exploitation, you can just use that production line for garrisons as well and have a more efficient production line. The only reason I can think of for producing them is for reconnaissance, the one area where they beat light tanks. Even then, it's not really worth the .5 extra recon.

That's why I am putting in a suggestion to add a percentage bonus to suppression for armored cars as you get higher in their techs. This would make it so that you have to use a fraction of the manpower for garrisons that you normally would.