Sorry, been too busy to get back to this!
As some have mentioned already, in the aforementioned games, armor is ablative. Once it gets breached, the internal systems can be damaged, 1 point of damage per box/circle. When a system has all of its boxes/circles filled in, it’s destroyed. (Basically.)
If you're looking for ablative armor, 1 point per point of damage stopped, that massively reduces things. The only one coming to mind immediatelt is Palladium, but it doesn't have hit locations, doesn't have detailed wounding rules, and has high enough SDC totals that boxes become a bit cumbersome. THe way it works in Palladium: to hit in combat is 5+; any to hit roll under the armor's AR does damage to the Armor's SDC, if it has any left. Then, any left after the armor, or any to-hit above the AR but not a Nat 20, goes to personal SDC; Crits go straight to Hit Points, and (if using the intended but optional rule) any HP damage also does a lasting effect of some kind.
Oh, wait... Car Wars (from original Deluxe box on, at least) is functional as an RPG using the continuing characters rules (and noting that the skills list includes some non-combat skills from that point on until the relatively recent Car Wars Classic boxed set, but Compendium retains them.)
I've seen a lot of semi-ablative armor mechanics. Twilight: 2000 4E, 1 in 6 chance that armor ablates a point when damage breaches it. Several small press games have armor ablate one point per penetration, as do a few more from major publishers.
Edit: I just remembered a couple more: Epiphany 1E, and the Vapire Larp both have provisions for damage to armor when hit... cancelling the armor trait's positive benefits...
@Argyle King - GURPS Ablative isn't the same as, say, Car Wars ablative, at least not the last time I looked ijn the rules. In GURPS, last I checked, Ablative only lost points if damage dice were 5 or 6. In Battletech, each point of armor stops 1, and only 1, point of damage, before needing to be repaired/replaced. So with 15 armor, and a 5 point hit is stopped, there's now 10 armor left. Very common in detailed consim board games (SFB, Starfire, Battletech, Car Wars, Battlecars, FASA ST III SCS (albeit via counters on sheet, rather than marking boxes off).