Another thought - check PCA.org:
You may have to be a PCA member to see contact info but they have a Quest program where you can join for six months if you are shopping for a car. I just checked the site and used "Panamera" as search term in classified and a few 2010's and 2012's came up. One's a turbo.
In this case they are all supposed to be private sellers and often they are long time PCA members. It may not mean anything but it could also mean you're getting a well kept car from someone who is passionate about the brand. Obviously you perform due diligence anyway (or at least I would).
https://www.pca.org/browse-the-mart-classified-ads?keyword=Panamera&itm_field_ad_number=&sort_by=ds_created&sort_order=DESC
There is also Excellence Magazine (online). Excellence.com. You can search by key word. Dealers and private sellers advertise. THere can be a lot of overlap between Excellence, PCA.org and Rennlist but you never know....