[QoL] Tier 1 car parts don't show up in the level 1 tech tree and also they aren't known by default.
Why not just make them a default BP since you can find them everywhere anyway and they really aren't that useful once you get to T2.
The game design intention is for you to scavenge for the pieces during the early game, they're easily found at and around the roadside.
Better parts can be bought at the Vehicle Parts shop at the bandit camp or unlocked at tier 2 tech tree.
We've no intention of adding them to the workbench level 1 tech tree or adding them as default blueprints at this time.