If I recall correctly, there are issues with the dust shields on the front struts that detatch themselves and rattle in cold weather. I cant recall issues with rear suspension rattles. However my own 2010 i30 hatch had a rear suspension rattle last year that was reported @ its second service. I was told that both rear brakes (handbrakes maybe?) were freed off and reassrmbled. I was very cynical of course - but indeed the noise has gone and not returned.

I have a 2010 1.6 hatchback and it has been investigated twice since new (1st & 3rd Annual Service) with knocking noises from the suspension. Turns out there was a recall regarding the suspension and on each occasion they advised that the "Bump Stops" had fallen. Both times this was fixed under warranty.