IMHO it is more important to move the pad along the contours of the car's suface rather than trying to go first one way and then the other. With a polishing machine you need to keep a constant pressure at all times. This is much more difficult when the car has so many contours as on the Z3. Just make sure you get good overlap between strokes. I did mine this weekend using this method and got excellent results. I used a setting of 4. First with Griots Machine Polish #2 and then #3. Topped it off with Zaino. Looks great! I tried this several months ago and had the PC set at 3 with less than spectacular results. A setting of 4 seems to be optimum. Thanks to FredR for that suggestion.