Also being the owner of a black car ( actually in for respray due to scratches) ive found that removing LIGHT swirls is not impossible but does take time, cutters on black paint is not good and a bit harsh in my opinion, i have used mothers swirl reducer and an electric buff for hard stuff but lighter marks will come out with a good hand polish.
Wash your car well with 2 BUCKETS of water , one for the soap and one to rinse your sponge in so you dont transfer the dirt youve just washed off back onto your paint ( another way of creating swirls is dirt transfer).
Dry your car and put it in a nice shady place, grab a block of detailers clay and give the mini a good rub with that with a squirty bottle to lubricate the clay bar turning and remoulding the clay as you go when one side becomes dirty, the clay bar will remove all contaminants from your paint basically leaving it raw but smooth as glass and will remove a few swirls to boot.
Apply the swirl reducing polish to one panel at a time with a good quality cloth and wipe off buffing lightly BY HAND.... hopefully just a good hand polish with that will remove most of your swirls but if not pepeat it again by hand and if still no sucess grab a buff and give it a polish with good quality polish( not any sort of cutting polish or swirl reducer), if that works bung on at least 3 coats of wax to protect your nice shiney paint.
polish will make the paint pop but the wax will lock in that pop
Mate, it may work and it may not, it all depends on how the car has been looked after as a whole and how deep the swirls are.
Hope this helps and hope it works for you
