RM Auctions has added a second day to its forthcoming London auction, which will be dedicated to the sale of the 'Ultimate Mercedes-Benz Collection'.

'One of the great, iconic, pre-war grand tourers'

The auction with take place on September 8, with 74 magnificent examples from the German marque offered from a single-owner.

"A single-owner collection of 74 cars is rare enough at auction, but this ultimate collection of Mercedes-Benz automobiles contains some beautiful examples of very important cars alongside some wonderful cars which are desirable, interesting, and rare in equal measure," said RM's managing director Max Girardo.

Starring in the sale will be two beautiful 540k Cabriolets, a model which is described by the auction house as "one of the great, iconic, pre-war grand tourers".

A 1938 Cabriolet A will sell with a £1.9m-2.5m ($2.8m-3.7m) estimate, while a 1938 Cabriolet B is expected to make between £1.1m and £1.3m ($1.6m-1.9m).

A 1936 Cabriolet C will follow, valued at £850,000-950,000 ($1.2m-1.4m).

RM's Peter Wallman added: "The Ultimate Mercedes Collection includes a variety of rare and fun models, including a very sweet 170V Roadster, a beautifully presented 1952 170DA Pickup, and an interesting 170 SV Ambulance.

"To round things off, no Mercedes collection would be complete without the evergreen and hugely popular 190SL, whether the 230 Pagoda models or the luxurious and advanced 1966 600 Limousine."

At the 2012 Pebble Beach Concours d'Elegance, a 1936 Mercedes-Benz 540K Special Roadster sold for $11.7m, placing it within the top 10 cars ever sold at auction. It was one of just 30 ever built to top-end specifications.

Values for rare Mercedes cars are expected to rocket following the sale of Juan Manuel Fangio's 1954 W196, which set the world record for a car sold at auction at $29.6m, on July 12.