armor works only when you are in the vehicle, it's a game limitation

I thought it is related only to modded armor, so this also applies to hoods of modded vehicles?

Not directly related but: usually vehicles from your mods get damage to trunk lid and once trunk lid is broken damage goes to gas tank, but for instance on PD Challenger damage goes direcly to gas tank all the time and trunk lid doesn't take any damage from any impacts. Another would be Rear Bullbars, those don't seem to protect anything at all, on some vehicles they don't even take damage. Any idea why is that?

I also noticed the same as somewhatfrog on my beautiful Camaro. On my server I keep wrecking the gas tank instead of anything else in the back part of the car.
Not a huge issue since I can always fix it but it is a somewhat annoying bugsie.