agency estoppel

let's just assume for the sake of the question that you are indeed the "owner" of the property, you hu*****and is usually considered as your agent, who has the actual, implied, or simply apparent power to act on your behalf.

under the agency principle, unless he knows clearly that your hu*****and has no right to act on your behalf, you are estopped from claiming that your hu*****and's action does not bind you.

under the agency principle, if you hu*****and really do not have the authority to agree to the deal, you may file suit against your hu*****and to recover the damage, because he is not acting within his power.

and that's not all. even though the title of the car is in your name, depending on your state law, you hu*****and might have interest in that car as well. so the assumption we mentioned earlier might not stand be begin with.