Reporting a 6months old Kx. Car starts to have minor rattling sound, guess i spoke too soon that i have no rattling issue. But at the moment the sound is very minor and mostly from start of fresh when shift to D gear and the timing between brake release till acc pedal where your car starts to move a little. Once car moving in 5km or so the rattling stops.

So it's a small window of 3-4 secs minor sound. Could not tell which part exactly as it's somewhere around inside the HU. Very hard to determine unless dismantle the HU to check. Actually is some what still acceptable is i care less, but i can say due to Cerato can be quite quiet on stops and idle, so many of us will find the sound happen NOT pleasing to a quiet car.

If you have the rattling sound, one more possibility is the CD/DVD in the HU, i experience louder rattling in idle to moving from 0-5km, then i realise my CD in the HU. Ejecting it reduces the rattle sound a lot.