Essentially, you have a part so basic in function that it doesn't need to save any data when removed and turned into an item (lightbar, bumper sticker, a part as a crafting item, any simple generic_ part, etc.) that it, well, doesn't do that when you wrench it. We're talking doesn't actually do anything when damaged or totaled, doesn't take any subparts (or cannot be removed when they're installed), absolutely nothing on it needs to be saved and reloaded when it is wrenched. You basically just get a fresh item!

Ahhh, I see. In that case perhaps I could also throw it out there, a parameter for VMs that keeps them from being saved as NBT data? I'd say assume they need to be stored by default, with the parameter selectively marking VMs for not-storing?

VMs are designed to modify existing variables, not create/store new ones. If those get trashed, then such things will need to wait for the animaton overhaul I'm working on.

Eerrrr... you mean I wasn't supposed to be using those to store things like vehicle mileage, and the like? Uh oh. It's not a big request anyways, no worries.

Addressed in 22.14.0.

So, I could add this, but I also should have my code be smart enough to realize that no NBT data of value has been saved, so really this is more of a bug to allow re-stacking of parts without differences VS anything else. Will track as a bug rather than a feature.