Has any RPG system ever used…

[Dannyalcatraz]

HERO can do a mix of non-ablative and ablative DR, plus other defenses no problem.

The trick is PCs actually losing capabilities as they take damage, and only from those damaged locations. I could do THAT with HERO, too, but it would require a lot of power/character or campaign specific limitations & disadvantages- Focus being #1 on that list. (And option losses due to interfering with a Focus tend to be all or nothing.) So, for the most part, HERO PCs tend to retain all of their options intact until they actually drop.

 

[Mustrum_Ridcully]

I think I played such a system at some point. But I could be misremembering it, and it has been over 10 years by now. I think it was Space Gothic. It was from a German RPG company and I don't think it's around anymore, at least not actively so.
... Just looked it up, it's available for download for free: Space Gothic - kostenfreier Download - Regel- und Modulbücher für einen echten Rollenspielklassiker aus der Vergangenheit
The character sheet seems to confirm my memory. It seems that you have a base hit point value, and then each body location has a hit point value modifed by 0-3 points down from your base hit points.
Armor is variable damage reduction (for example 1d6+3 for some kind of bulletproof vest or something.)