Fundamentally agree with vehicles needing a lot of work to get up and running as a semi-rare item.

Though many factors involved which aren't taken into account which makes them near impossible or not worth fixing up.

-far too easy to remove/add parts. (needs a bottleneck) So anyone can salvage parts off a car spawn further reducing it's ability to be fixed up.
-Spawns with too many parts needed.
-Car Parts too wide spread and uncommon. (especially the specific wheels needed)
-Players can be shot and killed while they focusing on getting parts together which resets their "progress"

With all the above combined, we aren't seeing vehicles being driven or used at all. It would create such a great tone for atmosphere and make the world come alive even seeing other players driving in the distance or hearing an engine etc. There's also the ability to hijack/kill and take another players car and thus them "losing" it as well. So there's a big incentive to improve and balance it better to have vehicles up and running.

Suggestion for the bottleneck: Players require tire iron to remove/add wheels and a wrench to remove/add radiator/battery. This means if you want to get a car up and running, you need to dedicate yourself to it by getting the right tools. This also prevents other scavengers from just ruining progress on a car and reducing them to nothing by easily being able to take parts.