For the 1966 vintage, the Citroen DS19 was joined by a new model, the DS21, equipped with a square engine (90x85.50 mm) of 2175cc and 198 horsepower, The maximum speed was 175 km / h, i.e. in line with the performance of a Mercedes 220S or a Jaguar MkII 2,4 displacement and cost much higher The DS21 paved the way for a series of mechanical developments which eventually led to the DS23. The DS remained in production until 1972.