The 3045 cc engine of the original D6 placed it in the 17CV car tax band which, for many contemporaries, would also have defined its position in the market hierarchy. During its long production run the car underwent a succession of changes, many of which involved enlargement or modification of the six-cylinder engine. During the 1930s there were, for some of the time, two or three different engines sizes offered. Principal changes and differences in engine sizes were marked by changes and differences as to the suffix at the end of the car’s name, generally reflecting differences in fiscal or actual horsepower. For some purposes it can be helpful to think of the D6 as a succession of closely related individual models, but the basic architecture of the chassis and engine did not differ radically between the different versions.