You might not know this.
Structure parts give their HP bonus to the cabin.
But when your cabin gets low on hp, the structure parts keep their individual hp.
So essentially you get double the hp bonus from structure parts.
And the hp bar you play the game with is only half of what your car can take.
That’s a bit more complicated than that because if any structure part is striped (destroyed or just lost because not linked to cabin anymore) you instantly lose the HP it gives. So yeah in a perfect world you get double HP if a structure part gets reduced to 1 HP and is left alone but that won’t always be the case. Usually I would say it’s like 50% more HP. Some structures will tank some damage and survive, some won’t.
Some weapons like Acari and incinerators that do massive damage to all parts seem to do nothing at first but any hit after that will hit you build like it’s made of paper because many low HP parts will be striped if you are hit by an aoe after that.
Sure the game get much more complex with area damage and being shot from all sides.
But after years i still see players with very exposed cabs at their front, with structure parts at the sides and back enveloping the explosive parts.
Maybe they will put those explosive parts below their cars and structure part at the front after reading this