One-off vehicle

In the field of vehicles authorized to drive, a one-off vehicle is a vehicle that was manufactured only once. The production of unique vehicles is reduced to one unit in each case.
The easiest cases to analyze are those of cars and motorcycles. Unique automobiles and unique motorcycles are usually kept and displayed in museums. Aeronautical vehicles, with notable exceptions, are not preserved in the same way (due to accidents and disappearances). Naval vehicles feature a myriad of unique models. A non-exclusive base of examples could be the field of sailing and motor yachts.
Some cases of non-legalized vehicles may be included in this article if they have particularly noticeable characteristics (engine, chassis, body, etc..).
Origin of one-off.
A one-off is something made or occurring only once, independent of any pattern. First used in 1934, this term is employed to differentiate singular items from those in a series: e.g. "the Lincoln Futura was a one-off". It has been suggested that it is a misspelling of "one-of", but this etymology is not supported by sources such as the Oxford English Dictionary.
Cars.
Before mass production, automobiles were handcrafted. First the whole car and then only the body on a factory-provided chassis. There are many unique specimens of that time. Many customers made the car custom-made. Of that mass of unique cars it is only good to expose a few. Those that, besides being in a museum, have some remarkable features.
Alfa Romeo 40-60 HP Castagna.
The house A.L.F.A. Manufactured a 40/60 designated street car. Designed by engineer Giuseppe Merosi, it had a 4-cylinder in-line engine (with camshaft and cylinder head) and provided 70 hp (52 kW) with a top speed of 125 km / h. In the racing version, the power reached 73 hp (54 kW) and a speed of 137 km / h.
In 1914 the Milanese count Marco Ricotti commissioned an aerodynamic body to the specialized firm Castagna that allowed the speed of 140 km / h. This unique model was officially called "aerodynamics" and popularly was "Siluro Ricotti." 
1922. Doble steam cars.
From 1922 the Double brothers built the C, D, R and F. Series models Virtually every unit was unique, with significant changes to the chassis, boiler, engine and body.
1924. Hispano Suiza "Tulipwood".
The extraordinary and well-honored Dubonnet (the heir to the snack maker Dubonnet) commissioned a racing car in Hispano Switzerland based on the Boulogne model. The bodywork was commissioned to Nieuport, an aircraft manufacturer. 
Despite the luxurious appearance it was a race car. It was sixth on the Targa Florio and the fifth on the Florio Cup.
1931. Hispano-Suiza J12..
This luxury car was stripped naked, with only the chassis and engine. All J12s were unique. The engine was V12 at 60 degrees. The engine block was machined from a 313 kg casting block. The crankshaft rotated on seven bearings. Each cylinder had two valves operated by rockers from a central camshaft. According to the designer, Mark Birkit, this solution (apparently less sophisticated than the camshafts in the cilinde head) was chosen as less noisy.
1938. Phantom Corsair.
The Phantom Corsair was built as a two-door [[Sedan (car) | sedan]) for six passengers. A futuristic body was mounted on a Cord 810 chassis. This car was the result of a collaboration between young Rust Heinz (heir to the food industry tycoons Heinz) and the signing of bodywork Bohman & Schwartz. The mechanics of choice were the Cord 810 with a Lycoming V8 engine and front-wheel drive. 
Manufacturing intentions were void of the death of promoter Rust Heinz in a car accident.
2006. Ferrari P4 / 5 by Pininfarina.
American James Glickenhaus commissioned Pininfarina to create a special P3 racing body. The mechanical base was the Ferrari Enzo. The result would be designated with the reference Ferrari P4 / 5 by Pininfarina, authorized by the Ferrari house. 
[[Rolls-Royce Sweptail]].
It was the costliest car in the world at its debut in 2017.
Motorcycles.
1955. Guzzi Otto Cilindri.
[[File:Paris_-_Salon_de_la_moto_2011_-_Moto_Guzzi_-_Otto_Cilindri_-_002.jpg|thumb|Moto Guzzi - Otto Cilindri]]
The engine was a water-cooled 500cc V8. Two camshafts (4 trees in total) driven by a cascade of toothed wheels. It offered a power of 78 hp (58 kW) at 12000 rpm and weighed 45 kg. It was designed by the engineer Giulio Carcano.
The motorcycle broke the speed record with a speed of 280 km / h, a mark of would remain for 20 years. 
1991. Britten V1000.
[[File: Britten V1000 01.jpg | thumbnail | Britten V1000]]
This New Zealand motorcycle with very unconventional solutions proved to be very competitive in racing. Apart from the initial prototype, ten units were built with noticeable differences.
Aircraft.
1940. Grumman XF5F-1 Skyrocket..
Specially configured military twin-engine aircraft. 
[[File: The latest type of a Grumman Navy fighter - NARA - 195921.jpg | thumbnail | center | Grumman XF5F-1 Skyrocket. ]]
Airships.
1984. White Dwarf Airship.
[[Human-powered transport|Human propulsion]]. 
Boats.
Most vessels are unique. Series, even small series, are a rarity.
The present article presents only a random sample of vessels interesting for some concept.
1976. Bris II.
Small yacht 5.90 m long designed and built by Sven Yrvind (inventor of [[Bris sextant]]). Sailboat and owner starred in numerous ocean crossings..
[[File: The Maltese Falcon (2906785674).jpg| thumb|"The Maltese Falcon"(2008)]]
1990. The Maltese Falcon.
It is a yacht 80 m long, 12.6 meters wide and a displacement of 1240 tons. The device is trimmed with three self-supporting shafts. The candles are raised (strictly 'unfolding') from the inside of the tree. The sail area is 2396 square meters.
2005. Mega-iot Black Pearl.
With a rigging similar to the Maltese Falcon, its length is 106.7 meters. The displacement is 2864 tons and the sail area is 2600 square meters. The candles incorporate solar cells.
References.
[[Category:Vehicles]]