Buick Century is the model name used by Buick for a line of upscale performance cars from 1936 to 1942 and 1954 to 1958, and from 1973 to 2005 for a mid-size car.
The model name Century came about when Buick was designing its first production automobile capable of reaching a speed of 100mph. The division needed to come up with a name. One of the Buick executives had returned from a recent trip to Britain, and told the other executives that the British referred to going 100mph as "doing the century". The executives liked the Century name and it stuck.
The Century was sold as the Buick Regal in Japan, as Toyota owns the right to the name Century.