SWMBO is always adjusting the sun visors in her Kia Picanto3 and my Octavia Combi. Alarming knocks and rattles are caused when she does not clip the visor rod back. Sounds silly I know, but in my Octavia it sounded like bottles or cans rolling around under the passengers seat. In the Kia, very loud knocking and BRAAAP. 

Oh well. I also got a zero response on the Kia forum. We must have two unique noises in our vehicles. 

Had my Mum in my VRS yesterday, we went to the odd shop. Whilst driving home, there was something rattling a good 'un over at her side. I said 'dig around in the door pocket can you, something in there is making an awful noise. She goes digging round - noise still there. After a while and my increasing annoyance, I had the poor old woman extract everything from the pocket - she was sitting there with a lap full of random stuff. Noise still there.

 

In the end it was driving me so mad, I had to stop the car. It took a good 10 minutes of frustration before I realised that she hadn't QUITE wound her window up into the frame, although there was no gap to show it.

 

She got the hump with me for being so dramatic and we had a grumpy ride home sorry Ma!

Worked with a guy whose family ran a garage, they had a customer come in complaining of a rattle from the rear of the car, the customer had been going to another garage every few months as they would fix the rattle but it and it would inevitably come back after a few months. Turned out the number plate was loose and the other garage had been stuffing some of that white packaging Styrofoam behind it, which would degrade after a few months and the rattle would come back.