How long did the carnage remain on your hood/trunk? The longer it sits (notice I said "SITS") on your paint, the more likely it is that it will eat into it - depending on the foul perp's diet.
I'd try Meguiar's Clay Bar over the affected area first, then use their cleaner/polish and follow up with some elbow grease and a good wax. If that doesn't do the trick, then the acidity in the poopage might have eaten down into the clear coat and you will have to have a professional at a trusted body shop take a look at it.
Wet sanding and polishing doesn't mean repainting. All new (quality) paint jobs are wet sanded and polished after the final clear coat is applied. However, if the car is new, I would think there would be some kind of protection on the factory paint...??? I can't imagine it being quite that temperamental.
