I have some horrible scratches/swirls on my running boards. And an equal amount on my "plastic chrome" on my grille. I have tried all megs chrome polishes and some 3m smr but nothing does the trick. Any ideas?
Unfortunately, at least in my experience, once chrome (real or "plastic") gets scratched, it stays scratched. The only solution is to have it replated/replaced. The chrome on my XJS was scratched before I took (new car) delivery, and I've just had to live with it.
Try to keep it protected, as the scratches can hasten failure of the plating.