This is from ANTS, the french agency that handles vehicle registration. It might help.
If you inherit a vehicle following the death of a loved one and wish to keep it, you must have a new registration certificate (also called a “carte grise”) issued in your name.
If you wish to sell it or give it to a third party, you must also have a new certificate of registration issued in the name of the heir(s).
if the sale takes place less than 3 months after the death of the holder of the registration certificate,
if, since the death of the holder, the vehicle has not been driven on roads open to public traffic.
For more information on how to inherit a vehicle: https://www.service-public.fr/particuliers/vosdroits/F1480
To apply to the Ministry of the Interior for vehicle registration following death or inheritance, you must:
authenticate yourself with the France Connect device ( What is France Connect?). This account allows you to be informed of the progress of your approach and to exchange with the department in charge of the file, which may ask you for additional information or supporting documents if necessary;
Select the "I wish to make another request" approach from your "vehicle space";
Select the "Report a change in my personal situation" section
Transmit in digital format the supporting documents corresponding to your situation. To ensure optimal processing, check the legibility and size of your documents (max. 1MB per document);
Tick the commitment boxes and pay any taxes by credit card, to finalize the process after the Ministry of the Interior has checked the file.
Transmit the following documents in digital format:
In any case:
Proof of residence less than six months old;
An application for a registration certificate for a cerfa vehicle n°13750 ;
the previous registration certificate;
a document proving the status of heir:
or a certificate from the notary responsible for settling the estate certifying that Mr. Mrs..., born (e) on... to..., died (e) on... to... and that, in the estate, there is a vehicle (with indication of the make, registration number and vehicle identification number);
-or a deed of notoriety drawn up by a notary;
-or a death certificate accompanied by a certificate, signed by all the heirs certifying that there is no will, nor other heirs of the deceased that there is no marriage contract and that there are no lawsuits or disputes in progress concerning the status of heir or the composition of the estate.
In the event of joint heirs:
a letter of withdrawal from all other heirs in favour of the person applying for registration of the vehicle or a certificate from the notary stating their agreement to allocate the vehicle to one of them.
If the application for registration is made in the name of a third party to the estate:
A certificate of transfer (cerfa n°15776) established with the heir(s);
A certificate on the honour of the heir(s) who had legal custody of the vehicle certifying that the vehicle has not been driven since the death of the holder of the registration certificate;
Proof of roadworthiness test.
Translated with www.DeepL.com/Translator