As others have mentioned, the trick is very clean wash and dry media and reduce the friction passes. For the necessary friction passes keep the pressure real light. After the wash with a foam gun and final rinse I use the drip method and a leaf blower dedicated ONLY to car drying. Whatever water is left gets a very gentle wipe with perfectly clean WW MF towels.
I also have BSM and have all but eliminated introducing swirls or scratches by being extremely careful. It can be done.
I will also agree with those who suggest your fine scratches may have been there at delivery. They can be removed.
M3 + trailer hitch = oxymoron