If his name was on the title (regardless of whether your name was on the title, too) then he probably had a legal right to sell, trade or give away the property. When your dissolution proceeding asks about the equitable division of property, though, you can argue that the value of the car should be on his account.
[In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship.]
If the divorce has already been filed and the other party has been properly served then your husband is likely in violation of what are called Automatic Temporary Restraining Orders that prohibit the party from selling, transferring or concealing community assets without the other party's consent. If this is the case, then a motion needs to be brought describing what husband has done and request either the court order title be changed back (which might be a problem because now it is in mistress' name and she's not a party) or that you get the full value of the car at the time of transfer.
You will need to get the value of your car from Kelley Blue Book to have some written documentation as to the car's value if getting the dollar amount. Husband's conduct might also warrant the court to decide whether he pay attorney fees or costs for having you to file the motion including possibly sanctions. Different judges treat this differently so consult with an attorney in your area.
If the divorce has not begun then there are no restraining orders in effect and none of this answer applies. At most, it's a fiduciary duty issue. You should provide more information as to if the divorce had begun at the time of the transfer.
This is not intended as legal advice and does not create an attorney-client relationship.
You likely can't get the car back, if he had title to the car in his own name, or if title was in "his name OR your name", because he had the power to transfer title to the car. However, if there was a pending divorce case between you and your spouse, his transfer would have been a violation of the Automatic Temporary Restraining Orders on the reverse side of the Summons. Also, if you and he divorce, you could claim that he violated his fiduciary duty to preserve the community asset, and the equity in the car could be credited to his side of the 50/50 property division, entitling you to distribution of an equal additional value of community property.
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