It’s not every day that one of the rarest cars in the world comes up for auction, and it’s even rarer still when that vehicle forms part of the legacy of one of the world's most intriguing and famous individuals - Howard Hughes.

Hughes may be best known for his construction of the wooden 'Spruce Goose', which currently claims the record for the largest flying boat ever built, but the industrious American socialite also built several other interesting works. As an American aviator, industrialist, and film producer/director, Hughes became one of the richest men in the world - but his wealth never stopped him from building astonishing machines to help him break world records. This is where his work as an aviator meets the automotive world, with his heavily modified limousine.

Beginning with a 1936 Lincoln K Model V12 Limousine, Hughes reportedly took the car and converted it into what he thought a 1936-37 Boat Tail Speedster should really look like. After a lengthy process during which the entire car was redesigned and restructured, the result was an astonishingly aerodynamic vehicle that hence became known as the 'Aero-Mobile'.

Hughes reduced the weight of the car by "thousands of pounds", and coupled with a modified engine and exhaust system it was able to cruise at speeds in excess of 100mph - virtually unheard of in that time for a passenger car, but somehow fitting as a car to match Hughes' nature as an adventurer and aviator.

With its classic good looks at the front and the home-made, bolted-on appearance of a tail on the back, the car will not be winning any beauty contests in the near future, but as a testament to Hughes' ingenuity it is certainly second to none.

The car finally went for $1 million at the Leake Collector Car Auctin in Tulsa, Oklahoma on June 13. Other notable mentions included a 1936 Lincoln Model K Brunn Cabriolet that went for $187,500, a 1931 Cadillac V16 Convertible Sedan that sold for $185,000 and a 1932 Packard 903 Super 8 Coupe Roadster that was picked up for $160,000.