The District Attorney is holding your vehicle to either keep materials therein intact to avoid a problem with the chain of evidence and wreck his case. So, if there are personal items not related to your case that are legal for you to own and do not impeach your character, you have a good chance of getting those back if you ask your attorney to help negotiate that with the prosecutor. As to your vehicle, since you were arrested and it appears your vehicle was part of the arrest because either you were stopped and the police found the warrant you had, and towed and confiscated your vehicle to search later on or your vehicle was part of a search warrant the police had on you.