I know there are a few threads on this topic, but none seem to have been updated of late

2013 c70, about 4000 miles so far.

At low speeds (say even in a parking lot), there is a rattle that appears to emanate from behind the driver, as though it was coming from the left rear pillar.

This sound/noise only occurs with the top up

it takes very little to elicit the noise, minor undulations in the road will do it

feels like a loose heavy piece of plastic or possibly metal that is somehow balanced at a fulcrum point; takes very little to tip it back and forth at slow speed yet disappears at higher speeds, say on a highway, as though centrifugal force was pressing it down or back and prevent it from moving.

I have had three visits to dealer so far, they agree that there is a rattle, we test drove it together.

they have done some work on both the suspension and the top; lubrication and inspection and tightening of a number of struts or hinges in the top. They have also been in contact with Volvo central.

Each time I pick it up, we all agree its better, but not elimininated, and within 24 hours or so its back to where it was--once the sound had migrated to the area around right rear pillar

one important clue emerged this weekend; upon loading the trunk with 20 or so 1cu ft bags of garden soil, the sound virtually dissappeared--that would suggest its not the top at all.

anyway I am rekindling this to see if there is any more recent experience, thanks.