According to rustlabs you get other materials from the modules on cars. I do not have these settings in my config even after running for some time is this a bug or intentional, maybe another plugin conflict?

https://rustlabs.com/entity/shredder

I'm just now digging into how the Shredder works. This plugin only modifies the base "frames" of the vehicles. As of now, the only way to do what you would want, would require changing how much the blueprints for those modules cost to craft in the first place. The shredder gives half of the resources that the blueprint for the module costs. So doing this would screw over players on crafting the modules.