restoring faded rear plastic side panels

mine are black in the '68 Barracuda- not really bad shape - just faded /dull looking. Don't know if these are supposed to be high gloss or matte. Any tips on getting these into better shape? not quite ready to drop $900

1967-1969 Dodge Dart Parts | MP14003 | 1967-69 Barracuda / Dart Convertible Black Rear Side Panels | Classic Industries
35% off if you buy tonight....? Code NEL18