Starting as the Projet Tres Petite Voiture in 1934, Pierre-Jules Boulanger CEO of Citroen described the need for a minimalistic car, cheap to produce and easy to run and maintain. Very quickly a flat twin air-cooled engine was defined, along with interconnected front and rear suspension. By 1939 the 'snail' outline of the 2CV had been created, and the engine was now 375cc. The Citroen factory hid 250 prototypes from the Nazis during the wartime occupation, and it was difficult to do any development work. Flaminio Bertoni was involved with the 2CV design from the start. Nevertheless the 2CV evolved to become like a car until it formed into the 2CV we know for the 1948 launch. The first cars were given the designation 'Citroen A', but became 'Citroen AZ' from 1954; usually known as 'Citroën 2CV' from its taxation rating of 'deux chevaux-vapeur' Production cars had a 375cc 9hp engine until 1955 when it was uprated to a 12hp 425cc unit. From 1951 the AZU Fourgonette (Van) version was offered, and from 1958 a 4-wheel drive 'Sahara' model utilising engines in the front and rear of the 2CV. A 602cc engine from the Ami 6 was available in the 2CV6 from 1970. The 2CV had a 4-light shell until 1965 when most versions were given an extra window in the c-pillar. 3.8million 2CV cars plus 1.2million 2CV trucks were made from 1948-90.