its pish i used to have to sell the stuff n its utter pish!!!!
better of using meguiars 3step paint cleaner polish n wax.
I think the whole topic is very subjective (ooo bit heavy for 8am).
I had as part of my purchase from the renault dealer. Can't say I've had any problems with it (Supaguard).
Basically I've had it done at the time of purchase and over the last 18 months I have used other polishes, like SRP & EGP with P21s to finish. Recently changed to Duragloss, spray and dry after washing the car. Awesome shine (IMO). Next will try Duragloss with P21s.