rleven - - IMO all of the responses are pretty good, although somewhat conflicting. Here’s my take on it based on a lot of experiment:
PUPP-C has finer abrasives than Klasse AIO, so it isn’t as effective in removing very fine marring or hazing, but it does leave a more reflective surface. In my experience PUPP-C is almost identical to P21S GEPC or S100 SEC.
Something to consider is that AIO may contain chemicals that do a better job of prepping the paint for a topping of SG that another polish/cleaner may lack. :nixweiss
PUPP does give a slicker finish with better depth and reflectivity than SG, and it does top well with carnauba. But, it may not be as protective nor as durable as SG. :nixweiss
If you feel like experimenting, then you might try different combinations in a side-by-side test. You can easily go back down to bare paint and start over with the sequence that works best for you. If you don’t feel like experimenting, then I’d go for 1xAIO, 3xSG, several thin layers of either Souverän, P21S, or S100 paste.
Selling a used car really puts your ethics to the ultimate test! Good luck and enjoy your new CLK500!
Gary H. - - Even a brand new car should be clayed before the first polishing. Unless you took delivery straight from the paint booth at the factory there will be some “stuff� embedded in the paint. If you polish first, before claying, this “stuff� will be ground down to the level of the clear coat and can never be removed because later claying has nothing to grab onto. If that embedded stuff contains iron there is a good chance of getting tiny rust spots a few years down the line.