Obstruction and resisting

It sounds like they are already holding the car for too long. It seems to me that you need to ask your lawyer to get more aggresive with this police force and you might want to hire a civil rights lawyer who is from out of town to start a law suit and start issuing subpeonas. A suit against the department for conversion may also work with an order to show cause demanding return on the vehicle.

Your question contains a tautological ambiguity which makes answering difficult. It is not clear whether your husband's car was impounded in the first instance or the second. Depending on the circumstances if the car and its contents are considered "evidence" in a criminal prosecution against you or if it is subject to forfeiture proceedings for its alleged use in facilitating a crime you may encounter difficulty getting it returned until the criminal proceedings are concluded or until it is determined to not be subject to forfeiture. If the police have sought and failed to secure a warrant for searching the vehicle then that tends to weigh against any argument that the car and/or its contents are evidence.

If, as you indicate, the officer detained you "as retribution" for your having filed an administrative complaint against him then this would certainly constitute a violation of your civil rights as well as constitute an unlawful seizure of your person and vehicle subjecting any evidence thereby obtained to suppression (being ruled inadmissible in any case against you) assuming no independent probable cause to stop you existed.