Hi lotus18,
In the minimum, you need Z-1 and Z-2. I'd recommend Z-6 and also some kind of clay bar (Z-18 from Zaino, and there are other brands).
Z-18, and other detailing clay "bars" are just what they sound like, pieces of clay. A clay bar is used to remove contaminants from a car's finish to get it ultra clean and ultra SMOOTH. It really works well, but is a laborious process. I did it on my brand new '01 and noticed the difference. For a new car, many would say that it is perhaps not worth the effort, since the finish is so new, but read the info on the Zainobros website. The stuff about rail dust, etc.. is true.
You need Z-1 before anything. It is a pretreatment coat.
Z-2 is the basic polish. For a new car, that's probably all you'll need for polish. Go as many coats as you like.
If your car is older, Z-5 is recommended as it helps cover up minor scratches, swirl marks, etc..
Z-6 is this spray stuff that I really believe in. It can be used as a light cleaner (for say, dusting) and it significantly improves gloss. I love this stuff! Using it between coats assures that you are starting off with a dust free, glossy surface before you apply more polish. I use it after car washes to enhance the shine and it also seems to reduce static, allowing the finish to not collect dust quite as fast....
Other Zaino products are optional, read the website for more info.
Hope this helps.
-SJ
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DEP '01 EX no-navi