I found a site where this car is supposed to be built 4 times, based on Panhard Dyna X86. A picture shows it with license number 6982 R 75, which dates from 1950.
The Plantivaux shown here on AutoPuzzles has license plate 231 N 79, which dates from 1951. The 79 indicates the Deux-Sèvres, and Mr. Charles Plantivaux lived in Niort, the capital of this département. So I guess this was his own car.
The body of the car was made by coachbuilder Ets. Guichard in Fontenay-le-Comte (Vendée).