@BeSUA777 You can do it .
You want to use OpenIV & a 'mods' folder I reckon: http://openiv.com/?p=1132 (< There is a small tutorial under the video on that page).
Here is a simple video outlining the basics:
& also a Quick Start Guide for modding GTA V featured here on 5Mods.
@BeSUA777 try https://www.gta5-mods.com/misc/gameconfig-xml-dilapidated
For replacement cars, make sure you the cars in the correct patchday
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