Mercedes-Benz's luxurious 320 series was introduced in 1936 as a replacement for the 290 series.

Built initially in two wheelbase lengths, the 320 was down to just one from 1938 onwards, though a wide variety of open and closed body styles remained available, including a state-of-the-art streamlined saloon.

The 320's six-cylinder sidevalve engine started out at 3,208cc before being bored out to 3,405cc towards the end of production to compensate for inferior quality fuel.

Maximum power increased to 78bhp and overall performance greatly improved, while coil-sprung independent suspension all round ensured that the ride afforded the ultimate in comfort at all times.

The factory's sales literature was coy about top speeds, though models whose standard four-speed manual gearbox was complemented by the optional ZF overdrive 'autobahn' gear were reckoned capable of approximately 130km/h (80mph).

Hydraulic brakes were a very necessary refinement in a car that in saloon form weighed almost...