The DS project started as 'Voiture à Grande Diffusion' (VGD - mass produced car) soon after launching the Traction Avant in 1934. Pierre Boulanger and André Lefebvre decided to continue the progress they made with the Traction Avant, but with better streamlining. However, as development continued in secret through the war, the body design was very clumsy and one version was nicknamed the Hippopotamus. Flaminio Bertoni, designer of the Traction Avant took the ungainly body and revised its dimensions to create the aerodynamic shape we know today. But the shape kept changing, even in 1953. The engineering also developed, although the flat six engine had to be abandoned and a new version of the Traction Avant engine prepared for Projet D and Hydropneaumatic suspension was also developed. Launched at the 1955 Paris Salon as the 'DS 19',(a pun on 'Déesse', the French word for Goddess) was launched in 1955. The Traction Avant continued in production for a couple of years as a lower-price model, and in 1957 the cheaper ID 19 (a pun on 'idée', the French word for idea) followed. The ID had lower power, but also had fewer hydraulic assisted systems. The estate car model was launched in 1958 as the ID 19 Break. In 1960 the DS 19 was given more power, and in 1962 the front end was revised, with a cleaner nose and undertray that increased top speed and improved cooling. The Traction Avant-derived engine was replaced in 1965 with a new 1985cc engine for the DS 19, and a new 2175cc engine for the DS 21, and external driving lamps had been available since 1964. The famous 'sharknose' front appeared in 1967, with steerable headlamps on some models. In 1968 more power was given to the DS 19 and it was renamed 'DS 20', and ID 19 was renamed 'D Spécial' and a new 'D Super' model introduced as an ID 19 with the DS 20 engine. The millionth DS was manufactured in 1969 and in that year a fuel-injected DS 21 was launched, and this model was upgraded to the DS 23 in 1972 with 2347cc engine. The DS 21 engine migrated to the D Super five 5-speed gearbox to create the 'D Super 5 21'. Production ended in 1975 after 1,455,000 were sold.