Installation guide:
Add-on:
Run Open IV and enable EDIT MODE
Go to path Mods/x64/dlcpacks and drop copo folder into it
Then go to path Mods/Update/Update.rpf/common/data and right click on dlclist.xml and choose EDIT.
Paste <item>dlcpacks:\copo\</item> in it. 
Spawn name in game : copo

OIV:
Run Open IV and choose package installer in the items.
Find copo.oiv in your pc and choose it.
Install it and choose mods folder.
Spawn name in game : copo

Replace:
Run Open IV and enable EDIT MODE.
Go to path Mods/update/x64/dlcpacks/patchday3ng/dlc.rpf/x64/levels/gta5/vehicle.rpf and find and replace car files.