Here is the thing.
Meguiar's M09 and Menzerna FPII are really not going to do much of anything other then refine the surface of the traditional hard clear coat your Mercedes has. They are final polishes. The majority of polishing action you get when using these is going to be from technique and pad selection.
M205 is a final polish, but because it used a different abrasive system, it will actually do some correction.
There are a couple of factors you are doing battle with...
The hardness of the paint: Most Mercedes use a PPG paint system which as been called 'Cermaclear' which is a very hard, not very polishable paint.
The depth of the swirl marks: Often times we 'see' the frequency of the swirls but we don't know how deep they run. A few deep swirls is going to require far more polishing then very frequent shallow swirls.
Inexperience: This is over come with.... experience, so keep at it.
When you are not getting the cut you want from a desired product/pad combo you can change your technique to increase the polishing action.
1)Work a smaller section- Shrink your section from 24x24 to 18x18.
2)Increase pressure- Use enough pressure to compress the foam and slow (but not stall) the rotation of the pad.
3)Slow down!- Moving the polisher across the surface too quickly will greatly reduce the amount polishing action. This and not using enough pressure are the too biggest mistakes most beginners use.
4)Increase power- I generally use speed 6 for polishing.
If you need something more aggressive you might want to consider Meguiar's M105 or if you need something a little smaller and available locally, consider Meguiar's Ultimate Compound.
