I know this is an old thread,but I had the "rattling sound"
and found it to be the bushes on the rear dampers,I got these from the Kia dealer today for £1.60 each (2 per side).
it took me 2 hours to do both sides but I also removed the bracket which made the job a lot easier....Great tip...Thanks
Considering that my '55 plate has just had its 60,000 mile service 3 weeks ago,I was a bit miffed about 2 things.
1. The garage should have picked up on these bushes being worn,in fact one of them was virtually non-existant
2. The fact that they have deteriorated so badly for a 3 1/2 year old car.