I did the Zaino thing on my 4 year old 300m over the weekend (a test run for the big leagues when I do my Crossfire). It was a lot of work: Wash and dry the car twice, apply the clay bar, apply and remove polish twice, apply and remove gloss enhancer twice. Total time around 5 hours.

Is it worth it? At first I was skeptical. After a few days, however, I think I'm won over. The forecast here is for warm and dry weather, I'll be able to see how it does against dust but so far the results are positive. Also, it got rid of swirl marks left by a hack job car wash a while ago.

Plus, I think the Zaino instructions are quite confusing but once you figure them out and do it it's pretty simple.