Make the scrap buggy and uni-chopper craftable. Lets say you play on a busy server where vehicles and especially choppers are hard to find. It would take alot of materials but you could build your own. Example. A scrap buggy would take 6 metal tubes, 8 scrap metal, 2 screws and 4 reinforcing materials. You would build the frame in 2 or 3 stages and the final result is a scrap buggy that still needs engine tires etc.

The chopper would take a good bit more of course. It should take enough materials to make them a last resort if all other vehicles are taken.
Possibly make it similar to building a house where you have something like an old engine lift to act as cement mixer/crane and blueprints. Scrap buggy can be built within 15m of your small garage and the uni-chopper can be built within 30m of your large garage (cant be too easy to build a chopper).

Sorry, but i dont think someone would waste that much materials to build such an "crappy" car, which is available in each city atleast 1 time, because noone uses scrap buggy or apc
Theryre just to slow, almost no defense and not much item space.

I agree my material table is a bit over the top with the screws etc. I didn't put much thought into that portion since whatever i suggest will most likely not be the same as what the devs would do for balancing. Since the buggy is a "crappy" car maybe the ones we can craft are new vehicles that are actually good and the only way you can get them is to craft them.
Have them set up like houses where you can only build one. If the car is destroyed then you can build another. And being that this is the idea/brainstorming section of the forum please respond with actual ideas and not that its a waste. If you feel its a waste input an idea to balance it.