@MKE.  Thanks for answering my questions above.  So, No smoke!  Apparently modern synthetic oils and the CAT are stopping exhaust smoke.   I did not know that.

Also, thanks for the link about the Hyundai class action.  Interesting.  I'd guess that this matter may have been raised previously on this forum, but I can't remember it (not unusual these days .).

Please update the forum about the results of the various tests your mechanic carried out which, hopefully, identified the issue with your engine.

Cheers, TT

Nice intro  

 

Hello!
I'm MBC and I'm at my third i30 right now, I'm grateful to start my membership here, hopefully I can provide some useful info and I can learn from others that are, more likely, well much better informed than me.

I'm from Cluj-Napoca, Romania (EU). Here is a picture of my car a 2024, non facelift, PDE Hatchback with the 1.5 T-GDI mild hybrid and manual gearbox. In my country, the trim level is "Highway" which is the middle of the road right now as features. The color is Shimmering Silver.

Welcome

So in summary you have misting inside windscreen and loss of coolant. That sounds like a coolant leak, maybe at the heater matrix.
Normally any misting can be cleared using air-con, but not for you it seems.

Is there any sign of wetness on passenger side floor or glovebox area?
Any coolant on ground under car?

This may be worth a read: Heater Matrix blocked and leaking