OK has to be the 75th thread on black cars this week
NOOOOOOOOO to Tcut!!!!!!
If you want the car look new again, suggest getting someone to Machine Polish it for you as this will remove all of the scrathes on the surface.
If you are aiming at certain bad scratches, I recommend Meguiars Scratch X.
Wax is personal choice, good starter is P21s (now called R222) or Collinites 476 as a good hard wearing wax.
If you are polishing the car by hand, try Auto Glym (AG) Super Resin Polish (SRP).
Don't forget to seal the paint work once you have polished it.