Let me preface by saying I'm not owner, but i do know that you won't get good answers in this section. The fast and furious section might yield the better answers but asking at fb owner groups or bmw Malaysia forum is better.
That said, I've also been looking and researching into the F30 as well (but 328i instead of 320i) and here's some of the issues I've found
- steering rack knocking (can be fixed with repair kit)
- oil sump leaking (if it leaks, need to change)
- head gasket leaking (again if it leaks, need to change)

Iirc these are the main ones. So you'll need some cash set aside. And this is common sense, but don't tie down yourself into a 7 or 9 year loan with a car this old.

The F30 has been around since 2012 though