The Buick Gran Sport 400 was a variant of the Buick Gran Sport that debuted for the 1967 model year. The Gran Sport 400, which was also known as the GS 400, was only offered in a coupe or convertible body style, with a 400ci V8 sending power to the rear wheels. The famed Turbo 400 3-speed automatic transmission was available, as was a 3 or 4 speed manual. Production of the Buick Gran Sport 400 ended in 1969, when it was replaced by the Buick Gran Sport 455.