The AC Six was a series of sporty cars introduced in 1920. The Six was built in two Series, the first, from 1920-1929, and the second from 1932-1940. These cars were initially powered by a 1.4L inline six engine, but from 1922, a larger 2.0L inline six unit was used. This 2.0L engine was available in a range of tunings, designated by the taxable horsepower next to the actual horsepower (ex. 16/60). Production of the AC Six ended in 1940 due to WW2.