Make sure you get your husband to specifically say that you have a right to reclaim your belongings. Take the letter and any receipts or licenses to your local police detectives. They should be able to get permission from the detective running your husband's case.
If you don't have a key to wherever your possessions are stored and/or the car keys, call the non-emergency Police number. As long as you have something in writing from your ex stating the possessions & car are yours the Police can help you retrieve them.