Polishing compund is a good choice. It does have an abrasive property
so be gentle with it. If your car is under six months from date os manufacture
I would wait a bit. If it's more than 6 months old try the polishing compund.
If it's more than one or two years old it could probably use it anyway. You
will notice that the rag will turn the color of your car, this is normal. The
oxidized paint is coming off. You will also need to wax your car afterwards.
Before trying anything though test an iconspicuous spot to make sure that you
won't scrape all the paint that's left off. It's not that abrasive (not like
sandpaper) but has fine abrasive that leave a smooth finish when done. If that
don't work try some 600 grit sandpaper, than the compund than the wax.
Again be careful.
I'm not going to be responsible for whatever you try.