Short answer. It depends on what she believed. A legacy of another person's property is void if the testator erroneously thought it was hers. If she knew it was not, the estate may have to acquire it for you, and if it later became hers the gift takes effect after all.

What the law says

The legacy or devise of a thing belonging to another person is void, if the testator erroneously believed that the thing pertained to him. But if the thing bequeathed, though not belonging to the testator when he made the will, afterwards becomes his, by whatever title, the disposition shall take effect.

Civil Code, Article 930 — A Legacy of Another's Property. Read the full provision →

What the law says

If the testator orders that a thing belonging to another be acquired in order that it be given to a legatee or devisee, the heir upon whom the obligation is imposed or the estate must acquire it and give the same to the legatee or devisee; but if the owner of the thing refuses to alienate the same, or demands an excessive price therefor, the heir or the estate shall only be obliged to give the just value of the thing.

Civil Code, Article 931 — Ordering the Acquisition of Another's Thing. Read the full provision →

The hinge is what she believed, not who owned it

The legacy or devise of a thing belonging to another person is void, if the testator erroneously believed that the thing pertained to him. Void, because a testator can only give away what is hers, and a gift made under a mistake about ownership is a gift she never really made. Notice the qualifier though. The article does not void every legacy of another's property; it voids the one made in error. So the question a court would be asked is not simply whose car it was, but whether your aunt thought it was hers when she wrote the clause.

If she knew it was not hers

Then Article 931 may apply instead: If the testator orders that a thing belonging to another be acquired in order that it be given to a legatee or devisee, the heir upon whom the obligation is imposed or the estate must acquire it and give the same to the legatee or devisee; but if the owner of the thing refuses to alienate the same, or demands an excessive price therefor, the heir or the estate shall only be obliged to give the just value of the thing. Your cousin cannot be made to sell. What the article does is convert the gift into a charge on the estate, which is discharged either by buying the car or by paying its just value.

The after-acquired rescue

The second sentence of Article 930 saves a gift that looked doomed: But if the thing bequeathed, though not belonging to the testator when he made the will, afterwards becomes his, by whatever title, the disposition shall take effect. The words by whatever title are broad — purchase, exchange, inheritance, settlement of a debt. What matters is that she owned it by the time she died, since capacity to give and ownership are both tested at that point. So before concluding anything, establish who was registered as owner at the date of the will and who was registered at the date of death; those two facts do most of the work.

Two nearby provisions worth checking

Article 932 deals with the mirror case — a legacy of a thing that already belonged to the legatee when the will was executed is ineffective, though a direction to free it from an encumbrance is valid to that extent. And Article 957 revokes a legacy where the testator alienates the thing or transforms it so that it retains neither its form nor its denomination. Cars attract both, being sold, traded in and re-registered often. Gather the registration history, any deed of sale, and the will's own wording about the car before making a claim on the estate.

Cases citing this provision

These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.