The 540 K had its official launch in early October at the Paris Motor Show. It adopted a Mercedes-Benz overdrive transmission with semi-automatic gearshift. Shifting from third (direct) gear into overdrive did not require use of the clutch. Upon the transition to the 540 K, the same transmission was initially retained. The only modification being that what had previously been the overdrive was now the fourth (direct) gear thanks to changed transmission ratios.
Another special model that is often associated with the 540 K, which actually shares certain characteristics, bears the internal designation W 24 and is sometimes referred to within the company as the 540 K long. This was an experimental vehicle from August 1934 that was equipped with the M 24 eight-cylinder engine and a de Dion rear axle, possibly as a precursor to the planned successor to the “Grand Mercedes” (W 07). Four open tourers with a 3880 mm wheelbase were delivered between April 1936 and January 1937 to the Reich Chancellery and other government agencies, where they actually went into service.