BMW 6 Series refers to two generations of automobile from BMW, though both of them are base on the contemporary 5 Series sedans. The first was the E24, launched in 1976 to replace the 3.0CS & 3.0CSi (E9). In 2003, BMW released the all new E63/E64 which was available as a coupé and convertible. Models were the 645ci (later replaced with the 650i) and the 630i. The highest performance 6 series is the BMW M6.