Custom Gameconfig is NEEDED (or the game will crash).
If its outdated, try to find another one for your game version.
+ install this mods as well:
Heap Limit Adjuster (650 MB of heap!)
Packfile Limit Adjuster
For the car list (after the installation), start openIV and go to mods\update\x64\dlcpacks\gta5korncar\dlc.rpf\x64\vehicles.rpf\
Read the README file inside the archive
Car mods by: Gta5KoRn
Add-On method by: Alex9581