Actually, I helped start the Used Car Department at Tesla, and we were never officially known as CPO. Elon hated that terminology for some reason, so we landed on Pre-Owned. Eventually, they made us change it to Used Cars, I think as a way to further differentiate between the core business (building and selling new cars) and our express purpose, to do something with the trade ins. It always bothered me that we didn't offer an extended warranty for purchase to non-first owners, but now XCare does. Frankly, I think having XCare levels the playing field, and allows pre-owned car buyers a true choice for the first time.You cannot purchase an extended warranty directly from Tesla for a used car. You can purchase a third-party warranty from Xcelerate (X-Care) and will probably do better financially.
Regarding the whole "used" vs. "CPO" thing, I think NOW Tesla falls somewhere in-between. Once they stopped posting photos, they have assumed the responsibility of reconditioning cars as stated on their listings but just not to the level that they did before they changed from CPO to used.
Tesla's original CPO program was far and beyond the best CPO program in the industry where you would receive effectively like-new conditioning as well as a full 4-year warranty. Seat with a blemish = new seat. Curb-rash on a rim = new wheel. This program was unsustainable which is what I think led to the change to just plain used.
Now they agree to remediate certain issues like curb rash, scratches, dents, etc... if it's beyond a certain degree. I think this is reasonable but I am not crazy about the downgrade in the warranty to 1 year/10k miles.
As for whether they are CPO or not - CPO is defined as (source: Wikipedia):
Based on this - cars sold by Tesla would absolutely qualify as CPO. As to why they went through the trouble of changing the nomenclature, my guess is to avoid comparison to their original program which far exceeded what the definition above states.
Happy to advise, hit me up. [email protected] xcelerateauto.com/x-care and scroll down to the calculator to explore. Cheers, Brent Seavey, ex-Tesla OG.