Ok, here’s an idea.
Vehicle armour-type items have a bash and cut rating, but rather than outright block, it absorbs it and decreases the armour’s health. Any damage past that gets delved up into the frame and its components.
Split into two groups; Bash type and Cut type. Shock absorbers and weird blob-derived platings are good at bash but not at cut, and things like plating are good at blocking cut but not so much bash. You can install one of each, but if you do then your aerodynamics and mass ratings suffer greatly. Installing just one is fine though.
The amount they absorb can be balanced per tier based on what you want to be able to take it apart. Things without plating work as they do now.
Two types of plating modes for install: Full and slit, Full is 100% coverage but blocks vision, while slit is less coverage but it’s something you’d install on windows and quarter panels.
As armour is damaged, it loses its coverage and ability to absorb, exponentially, so up until yellow you’re fine, and yellow and below you’re progressively not fine.
Finally, add some sort of flexible tag to wood fences and such that halves return collision damage to armour, or add some sort of off road modifications that can defeat New England’s infamous adamantium bushes, cause current road mapgen is a pita.