In 1939, the BMW 321 was launched as an advanced development of the BMW 320 with the improved front axle of the 326 models, continuous bumpers and bigger tyre dimensions. During its production run from 1939 to 1941, the BMW 321 was supplied as a sedan or convertible. However, customers were also able to order the chassis and have a body made to suit their requirements by one of the large number of coachbuilders available at the time. By the time automobile production was halted in 1941 on account of the war effort, 3,637 BMW 321 automobiles had been produced - most of them (approximately 2,000 units) in the bodywork form of sedans.