Boy this is an easy one. ZAINO! the best polish products I've ever used. I brought the car home on July 15 and spent the day putting on the first coats. It gets a coat at least once a month. By far the best. For those of you that have just one coat, just wait til you put on more. I've used it for four years on the two PT's I owned and the shine and depth of shine is stunning plus there is no residue at all on your polish towel. I've tried a ton of other stuff but Zaino, Zaino, Zaino.
By the way I use the Z-6 after every hand wash, absolutely no car wash will ever see my car.
Pat