I did my first OIF with the old-new style wraparound PPE, and the 2nd with new-new style, and it was hotly debated which was better. The older ones are easier to do battlefield trauma care (in my opinion as a combat life saver), but the newer ones rode better once you adjusted. Both use the same SAAPI plates. Throat and neck cover, and a dangling groin protector with plate pocket, but they didn't issue plates for those. The cloth itself stopped alot of shrapnel (ESS ICE eyepro is awesome - upgunner took a faceful from a projectile IED angled to hit upgunners, lots of scars, but kept his eyes). There are also shoulderpad and sleeves for gunners. But plates are all only for centermass protection. Tourniquets are for everything else, or so the story goes.
I know its drifting off subject a bit to talk about PPE, but I think it you're talking about shooting a vehicle you're moving towards the subject of shooting a driver, and what a round could penetrate. I don't know what a 357 would do to a SAAPI plate - sure it would hurt, doubt it'd be fatal.