I am unsure how to fix the issue, I have looked around to see if anyone else has the same problem, but it seems quite rare. The closest I could find was someone posted that their car changes to default when approaching it, which seems to be happening here, but not only changing to default but becoming a mess. Their post had no replies.
I have tried re-creating a mod folder again, which didn't work, and tried reinstalling gta which also hasn't worked. I am not sure what to do next.
Strange thing is that these models have worked before, but I had to remove and re-create a mod folder as my game was crashing upon startup. Everything worked fine afterwards but then I came across this issue. It's also weird how one car works but others don't. This is becoming a huge pain!
I will also add that I haven't installed any graphic mods.