I have no experience of supaguard, but as an alternative method of detailing, I use Meguiars detailing clay on my BMW (I am close to ordering an XF). The clay removes contaminants and the paintwork, when felt with the fingers is far smoother than can be achieved using even the best polish. The car is then polished in the usual way, the theory being that the sooth surface achieved remains clean for longer. It appears to work well and the results are impressive. I understand that Meguiars is used by people who show their cars. It is stocked by some motor factors.
I have a feeling that if I buy an XF, itmay not be such a chore regularly polishing it to retain its looks.