Recognising that very expensive models could not support the company alone, Voisin introduced in 1921 the more economic C4. The standard body was very boxy, but the car could also be supplied as a sports torpedo or four seat open tourer or coup de ville. By 1923 the model had been developed with a small power increase and with more elegant bodywork. Front brakes were optional.

In 1924 the capacity was increased to 1328ccs and the front dynastart was fitted as standard. About 900 units were built and production ceased in 1925.