[Drop the hammer]

Compared to my F350, my grey and black nissan titans and my white armada, my AW E93 paint is hard. I usually use a Porter Cable DA with orange pad and med cut compound (maguires D300 or Maguires cut compound), and could not achieve the cutting action i wanted (normally this does the trick on my other vehicles for correction of swirls/spider scratches). It did correct about 50% of the minor spider scratches, but not any of the deeper ones. To get the deeper damage off I had to switch to the old rotary (which i don't use too often since it's a Makita tank and i'm old). Then I used the DA with a lighter pad and polish to get a perfect finish prior to seal and wax.
IMHO and experience it's pretty hard but I guess it's all relative based on ones experience. Probably could have gotten it with 2 or 3 more passes of the DA.