you sure it's not just surface 'dust' rusting? before you go getting all hyped up.. head up to autozone and buy a clay-bar for a couple bucks and see if that takes care of the problem.
what happens is there'e metal debris in the road dust/crap flying around and it affixes itself to our lovely painted vehicles.. sticks there.. and rusts. a claybar will remove it if that's the case.
now.. if you have a million little raised pinholes, then thats a different story