A 1939 Alfa Romeo 8C 2900B Lungo Touring Spider looks set to become the world's most valuable pre-war car.
The scarce vehicle, which features highly desirable Touring of Milan coachwork, auctions with a $25m estimate at RM Sotheby's Monterey sale on August 19-20.
The car is believed to be one of only 12 Alfa 2.9 Spiders remaining, and is one of only seven on the "lungo" long wheel base.
It is well known in collector circles. The Alfa has previously received an award from the Pebble Beach Concours d'Elegance for the quality of its restoration and has been a regular participant in classic events during the noughties, including seven 8C Alfa Tours between 1999 and 2013.
It could reach a top speed of 110 mph and cost around $1,500 new.
The present pre-war auction record is held by a 1936 Mercedes-Benz 540K, which sold for $11.8m in 2012.
"The Alfa 2.9 is a car of peerless engineering and extreme elegance - in my mind it represents the absolute highest echelon of car collecting and is a perfect fit for our sale during the Pebble Beach Concours d'Elegance week," commented Ian Kelleher of RM Sotheby's.
"From the standpoint of an automotive enthusiast, there is perhaps no more resplendent sound than that of the twin supercharged, dual overhead cam straight-eight engine of the mighty Alfa 8C at full speed. Without question, acquiring a car of such magnitude establishes one's collection at the forefront of the hobby."
The Alfa is one of five prestigious vehicles appearing at the sale from the esteemed Mann Collection, amassed by Sam and Emily Mann.
A 1956 Ferrari 250 GT Berlinetta Competizione "Tour de France" is among the five, with a $9m estimate, while a 1908 American Underslung 50 HP Roadster is expected to make up to $1.8m.
Please sign up to our free newsletter to receive exciting news about classic car auctions.