Now, this has been sorta suggested, but not as in-depth So if you look at the underside of the D-15 pickup, there is a spare tire, so it should be used someway, right? So there could be a key that you can press that could immediately change the tire with the spare in case you damage the tire, and this could be for any vehicle that has room for a spare, and if you have a mission where you have get from point-A to point-B, but keep the vehicle intact as much as you can, then this would help alot.
I have to imagine things like this are planned for when this becomes more game like. As of right now it is still basically a tech demo, albeit one of the most fun tech demos I've ever messed around with.
The problem with this sort of thing ((adding/removing, repairing etc.)) is the way the game handles jBeams currently doesn't allow for it. When you spawn in a vehicle, it generates a single physics skeleton. It doesn't differentiate between separate parts currently. It'd require major changes to the way the game handles jBeams for this. Maybe in the future, but not now.
This is going to be implemented, i'm sure of it. The reason the spare wheel is there currently is for realism.
Google quite literally takes the wonder out of life... now that I am no longer a student, fuck Google