Simon,
If those are real Fuchs 2L aluminum alloy wheels, then they are not painted (or an't supposed to be) - but are anodized aluminum (only the Steel, Mahle & P were painted).
Therefore, the black in your scratches are probably just dirt/road grime/brake dust made into an oily gunk & stuck in the scratches.
So just try cleaning them off with something like Simple Green & a soft toothbrush. Then if the scratches have any "lip" to them, you can sand it smooth with some120 > 200 > 400 & finish off with 000 or 0000
brass wool.
Don't try to smooth them out completely, because then you'll have an off look to that area, unless you have the entire wheel(s) restored by Al Reed or Harvey Weidman, etc..
Now if some DAPO has spray painted them, then I'd suggest that you strip off the paint with thinner or acetone, & evaluate their surfaces to consider if you can clean them up, or if you should send them to Al or Harvey.
They do kinda look like paint in your pic!
PS - Read through the Wheels & Tires nailed topic in the O&H Forum for more on the wheels.
PSS - Did you Standard Poodle come with your 914, or was that an option!?
Tom
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