A very special Mercedes will go under the hammer next month and it's expected to go for a fortune.

RM Auctions will be selling an ultra-rare 1955 Mercedes-Benz 300 SL Gullwing in October - and the guide price is £2.5m-3.2m!

It's number 20 of 29 alloy-bodied Gullwings and is finished in desirable silver within a red leather interior.

The car was delivered in '55 to a Swiss industrialist but then it was painted in ivory white. Despite the colour change, the car is expected to be of serious interest to car collectors worldwide.

Also of major interest to petrol heads is a racing Ferrari. The alloy-bodied 1959 Ferrari 250 GT LWB Scaglietti Berlinetta 'Tour de France' is one of just 36 "single louvre" examples and has a large competition history. It's estimated to make between £1.8m and £2.4m.

Other Ferraris in the sale include a 1958 250 GT Ellena Coupe (estimate: £250,000–£320,000); a 1970 Ferrari 365 GTB/4 Daytona, (estimate: £240,000–£300,000); and a superbly restored 1965 Ferrari 275 GTS, (Estimate: £350,000–£400,000) to name just a few.

A highly desirable 1952 Bentley Continental R-Type Fastback and a 1932 Rolls-Royce Plantom II Continental Drophead Coupe will also be sold, as will a large number of classic American cars and a 2008 Bugatti Veyron EB 16.4.

The auction will be held in London next month at Battersea Evolution. RM Europe managing director said: "There is always high anticipation for our London sale. We never fail to deliver a world-class catalogue of exceptional cars, and with the market having remained strong throughout 2012, we look forward to staging another wonderful sale in the UK."