*5,401cc supercharged straight-eight *180hp *Servo-assisted hydraulic braking *Documented history from new *In the present ownership for more than 45 years *Completely restored *Retains factory luggage *Highly authentic example Launched at the Paris Salon in October 1936, the 540K had an engine that developed 115bhp un-supercharged or 180bhp with the compressor engaged.

It featured the company's famous Roots-type supercharger system in which pressing the accelerator pedal to the end of its travel would simultaneously engage the compressor and close off the alternative atmospheric intake to the carburetor.

This system had been thoroughly proven on the preceding series of Dr Porsche-conceived S-Type cars, and in effect the 540K was the last supercharged production Mercedes until relatively recent times.

The gearbox was a four-speeder, but with a direct top gear rather than the overdrive ratio used on the earlier 500K.

With the supercharger engaged, the 540K's blown straight-eight gav...