My husband and I are separated he took my car it’s under my name only and he refuses to give it back can I report it stolen

If you purchased the car during your marriage, it is most likely community property regardless of being registered solely in your name.  Reporting it stolen probably will not be an effective way to get it returned.You should ask your divorce attorney to request temporary orders in your divorce proceeding awarding you the exclusive use and possession of the car during the pendency of the case.  If he refuses to return it then, your attorney can file a motion for contempt against your husband.  That is likely to be a far more effective way to get it returned.  Once you have been awarded the exclusive use and possession of the car by the divorce court, law enforcement may be willing to help you because his refusal to return it could be prosecuted as theft.  In my experience, police won't necessarily bring charges, but will stand there with you while you take the keys and drive away to keep the peace between you and your husband.