What kind of documentation do you need exactly to just get stuff out of your vehicle, not to get it released?

Title and registration. If impounded thru police and you don't have or titel/registration is in the vechilce, go to the courts and have them fill out the affidavit of ownership for it. Sister just went through this w Sandy's about 4 months ago.

And if its impounded better call them and the police aske them legal advice would be best.

Yes, title would be the best

Proof of ownership