LOL> The solution is simpler than you think.
Open your Trunk aka Diggi, and look for metal bars on roof which keep the diggi lid open, Pull on them. You will hear the same kring. Lubricate them with some good quality Graphite Lubricant.
Fun fact. Crush some Pencil leads and rub them, they act as dry lubricant so it doesn't catch dust. Works for interior squeaks too around dashboard or door knobs.
It could be some worn bush, doesn't hurt to get it checked. Usually Suspension springs make that kring but they do it regularly if dry. I understand whenever there is an incline, you hear the sound. It goes away sometimes and then comes back. Make sure your front S-Links are in good shape.