How to add completely brand new weapons and cars?

[dollar]

I want to add new weapons and cars with their new ID's, like, 10 types of pistols etc.

[user331323]

its impossible. you can use dff with existing IDs.

vehicle IDs Vehicle IDs - Multi Theft Auto: Wiki

weapon IDs Weapons - Multi Theft Auto: Wiki

[Addlibs]

You can augment the original weapon system if you replace original weapons with empty meshes and attach custom objects to player hands, however, this won't give you new IDs on its own and you'll need to code in a system to refer to and switch between these weapons yourself.