[monkeh]

My interior has rattling too. At 50k I'm surprised.
Being hybrid it's more noticeable when you're driving along in silence.
Pulling the rear trim out, driving along I haven't yet managed to identify it. I'll be making a friend sit in the boot and taking my favorite potholed private road...
Sound deadening will be added to the rubbish plastics, along with fabric tape to the contact surfaces on the plastic and clip holes. Maybe more sound deadening behind the factory matting/sound deadening and securing cables from rattling.
Did that on the chrysler I owned a few years back and it definitely made the world of a difference. No booming noises, doors shut with a thunk not a tinny clunk.