There are some spots on my Chevelle where the body shop didn't completely get some of the wet sanding material off. There are some little white, gunky smudge looking things (mainly down on the rockers and such, not too noticable), and some hard, almost gritty white spots on my back quarters. This is a black car so needless to say these are noticeable up close. Any tips on how to remove this? A rag/sponge, soap and water aren't really doing the trick, and was wondering if there is a special something I need. Thanks.

I used to detail cars at a dealership and this stuff is a pain to take off... AFTER IT DRIES!
If this was my car I would take it back and have them take it off. All of that white chalky stuff should have been washed off after the paint job. If it is the EXACT same stuff I am thinking of its a white buffing residue that washes off easily before it dries but is a pain to remove when dry.

Thanks, also to follow up, a lot of this crap is in my drip rails too and have no idea how to get it out.

Is there a different way for me to remove this stuff? The body shop is rather far away and I don't have another car to drive, so my car really can't see any down time. Is there a DIY way to remove this gunk?

Try a glaze, like Meguires Green #7 I think.