Heard from a dealer that the market for used 11 and 12 CS is soft.
Based upon the fact that the stock for new Cayennes is usually limited, I find it hard to believe that the demand for '11 and '12 is low.
Thoughts?

I think that's the common line salespeople use to lowball your trade-in's.

There is still a high demand for minimally optioned Cayennes, as exporters are buying them up for export to China. At least that's the case around here.

I was actually surprised at some of the prices of 11 and 12 CS's on autotrader.com!! There are quite a few in the mid $60's with extended 6 yr/ 100K mile factory warranties being sold by Porsche dealers, and majority have on average 15K or less miles on them.

Try finding out the Mayheim pricing for your car and inquire a few dealers for a reasonable pricing. When I tried selling my X5 50 with 5000 miles after three months of ownership a few weeks ago, this is the same line several dealers had been trying to tell me (e.g., how the national inventory for the V8tt is too high and how V8s are not doing so well, so on and so forth).
Guess what. After getting a reasonable price for a dealership, the dealership turned around and marked up my X5 by 8000 dollars over the check they wrote me. And they sold it within two weeks. It was kind of ironic how they were trying to feed me the same line that you heard.

https://www.manheim.com/

Dealers seem to commonly refer to the prices being paid at the Manheim auctions as well as with checking locally at appropriate dealers that might buy our trade-ins if the dealer we are buying from doesn't typically carry our trade-in as a used car. Manheim is for dealers only so access to this site is limited to them but I have had good luck in asking the dealer to show me the search results if they quote the prices being paid at the Manheim auctions.