With more translation, I found information that at least 4 of the Simca-Fiat Huit Deho's were built.
1) Silver in color, as it has an unpainted aluminum body. Built in 1938. Probably the car with the plate starting in "422-WO". If this is the currently photographed car, it has changed a bit since 1938. Various vents have been added, the doors have been removed, the grills directly over the headlights are gone. The current silver car has several taillights, all of which may have been added.
2) A blue car, also built in 1938
3) The highly visible (online) red car, with additional vents on the front. Engine sump has a plate labelled "Deho Paris", may also be associated with a builder named "Grolleau". There is an indication that cars labelled "Grolleau" were made by Grolleau after the war. Grolleau was an engineer for a company called "Bedaux". The forum post isn't clear about if the red car was built post-war.
4) A yellow car built by a garage named "Roux". If the red #3 is still a Simca-Fiat Deho, does that mean the yellow #4 is as well?