I've tried the following steps on lighter colored plastics with good results. Never tried it on black before. Make sure you follow the old adage to "test on an inconspicuous spot first".
If the scuff is mostly above the surface, I would try using a general purpose cleaner (like Eimann Fabrik Hi-Intensity) diluted a bit with water. Follow-up with a damp cloth and then a vinyl/plastic dressing (like 303 Aerospace or Vinylex).
If there is some minor physical damage to the plastic, I'd try using a plastic cleaner (like Meguiar's Clear Plastic Cleaner) between the general purpose cleaner and the vinyl/plastic dressing.
If the surface damage is more substantial, your best bet is to either seek out a professional detailer or learn to live with the scuff. Otherwise, you may wind up doing more damage than good. A stronger abrasive is likely to change the color and texture of the plastic, and heat guns are best left to professionals.