small cars achieved relatively satisfactory volumes, the slim margins at the lower end of the market provided a clue as to why the mainstream French auto-makers had tended to avoid it. In 1936 Rosengart himself was in financial difficulties and he transferred the company to a new organisation, Societé Industrielle de l'Ouest Parisien (SIOP). War and aftermath Production of the Supertraction was never large, and the factory was destroyed by the German Army following the German invasion. The business was able to survive the German occupation but did not produce cars during the conflict. After the war Lucien Rosengart, who spent the war in exile in the United States, returned to France and tried to guide his company back to the production of the small cars on which its success in the 1920s and 1930s had been based. Unfortunately, the several major manufacturers of France were by then making very small, economical cars that were very well suited to the conditions of post-war France, achieving sales volumes and economies of scale that the Rosengart branded car from SIOP were quite unable to match, leaving the Neuilly plant massively underutilised. Postwar The first small vehicle to arrive after the war was a light van called the Rosengart Vivor which was based on the LR4 model of the 1930s, but available only as a light van or, with side windows on the rear side panels, "break". Production peaked in 1951 with only 873 produced, and in 1953, a year in which just 373 had been manufactured, Vivor production ended. In October 1946 the company exhibited the prototype “Rosengart Super 5” at the Paris Motor Show at the instigation of Lucien Rosengart himself. However, support for the Super 5 from the Societé Industrielle de l'Ouest Parisien (SIOP) itself (which had held the controlling interest in the business since 1936) was less than whole hearted. Soon after this Rosengart disposed of his residual financial interest in the business that still bore his name, and seems progressively to have withdrawn his involvement. After the war Rosengart was not one of the automakers selected for inclusion in the post-war Pons Plan. The Pons Plan reflected government determination to structure the French auto-industry according to priorities identified by politicians and civil servants: exclusion from it created great difficulties in obtaining necessary permissions and materials. Little more was heard of the "Super 5", but late the next year,