First find out if its gelcoated or clearcoated. The approach for gelcoat will probably tear through auto clearcoat (rotary/wool/1500/meg's boat one-step) but a clearcoat approach won't make a dent in gelcoat (MUCH harder/thicker). If you can take it off the car to polish that will help a lot too. If its cleared, AIO is a good first step and if it doesn't work, just keep stepping up in polish aggressiveness until you get the results that you desire.
