Building a functional motor car requires a huge number of complex systems to work together, and to make a successful racing car requires a lot of focus on small details from ball bearings and fluid dynamics to the fundamental shape and powertrain of the car.
Because of this, most successful cars are built on carefully constructed platforms, often based on successful cars with a reputation for being fast and easy to control.
Here are some very notable exceptions.
Nissan DeltaWing
One of the most unusual racing cars ever made, the triangular DeltaWing was designed to take the rules of Le Mans racing to their limits and reduce drag as much as possible.
Unlike the other ambitious Nissan Le Mans failure of the 2010s, the DeltaWing was surprisingly competitive, managing a best finish of fourth at the Petit Le Mans race at the Road Atlanta race track.
Unfortunately, it was initially very unreliable and did not get much better before regulation changes ended all hopes of another car like it.
Rolls Royce Corniche Coupe
The Rolls-Royce Corniche was a gigantic and highly luxurious car, which meant that it raised a few eyebrows when it appeared on the starting line of the 1981 Paris-Dakar rally.
Entered largely as a joke, playboy Thierry de Montcorgé made a bet that he could run the rally in a Rolls-Royce, and after a lot of significant modifications that shed over 1700 pounds of weight from the standard car, it made the grid.
It did surprisingly well and finished the race, although after one of the steering arms broke off it was disqualified.
Volvo 850 BTCC-Spec
The British Touring Car Championship is typically home to modified and brightly coloured versions of the types of cars people drove to the race, which in the 1990s were almost exclusively saloon cars and larger hatchbacks.
The most striking exception to this is the gigantic Volvo 850 Estate car, which loomed over the competition and was surprisingly successful despite being significantly larger and less aerodynamic than its rivals.