If you lived in the day (I did ) one might occasionally see one of these cars on the street. The story behind the car is interesting in that it was originally developed for NASCAR racing. In NASCAR there are strict rules as to what modifications can be made to the engine of a car to keep a level play field for all participants. The engineer's at Chrysler figured out aerodynamics before anyone else and the role it plays in achieving top speed. By adding the extended sloped section to the front of the car and the wing on the back they were able to add another 8-10 miles per hour to the top speed. The second half of the story is that any car used by NASCAR under their rules also has to have a street version. Very few of these cars were sold to the public because of limited production and mainly because they were screaming to every cop in site pull me over. NASCAR added rules within a year or two banning the use of "wings" on participating vehicles because they were winning every race. These cars being sold to the public at Plymouth dealerships are icons of an era when Americans were truly free to dream and create. See the links below.
https://www.hemmings.com/classifieds/cars-for-sale/plymouth/superbird/1780514.html
https://classiccars.com/listings/find/all-years/plymouth/superbird