I can't comment to the replenishment of CPOs other than the fact that they were replenished in late March after I was looking for a couple of months. But how's this for conspiracy - when searching for a used S, I would normally search on my personal cell phone and request photos from that phone if I saw one that fit the bill. Inventory continued to go down gradually and then the one I had my eyes on disappeared. Figured I lost the opportunity but it showed back up a couple weeks later or so. Then, the inventory drastically depleated one day with the only S remaining in my price range being the one I had emailed about. I searched on my business phone to see if there was some error and found a large amount of "new" used inventory that I couldn't view on my personal cell. It felt like they were baiting me to purchase that one car before it too was sold. I started emailing for photos of cars I had no interest in but had similar attributes to see if by chance it would affect the declining price of the one I was actually watching. I don't recall that it did but prices definitely were linked to the number of cars they had available with similar attributes at any one time. I can't help but think they have algorithms at their disposal based off of search and/or interaction history. I started using evcpo more after the personal phone thing.
Yep, similar algorithms are being used by various sites where you can buy plane tickets, for example. Start looking at one particular trip and the price will go up, to make you rush the decision and buy overprices tickets.