1971 Plymouth Superbird Prototype
Inspired by the racing success of the original 1970 Superbird, Plymouth wanted more. So, they moved to design and testing the 1971 version. Since they redesigned the 1971 Mopar intermediates with a new body, they based the 1971 Superbird on their new line. However, they added a pointy front end and a new, improved double rear spoiler.
Once again, they thoroughly tested the car in wind tunnels. However, the sudden change of rules implemented by NASCAR officials canceled the project. To tame down the raging speed wars, NASCAR decided to limit the displacement of the engines to 302 inches or 5.0-liters. This slowed the cars down, yet made them extremely aerodynamic.
Sadly, since the 1971 Superbird was an expensive project, the car was obsolete. So, Plymouth canceled the model at the last minute after building just a few prototypes.