My black SRT took multiple passes to get rid of the swirls and water spots.

Used a Porter Cable 7424 orbital.
Used Griot's Garagce Machine Polish 2 with orange pad.
Sonus Swirl Buster with Sonus Swirlbuster pad.

Then topped it with Maguiar's NXT applied with fine black pad.
Sonus Acrylic Glanz sealer (rebranded Klasse product).

You can get some great tips from www.autopia-carcare.com