A magenta Hai 450 SS prototype debuted at the 1970 Geneva Auto Show. It had a 6,974-cubic-centimetre (425.6 cu in) V8 from Chrysler positioned behind the two front seats. It took its name from the output of the engine, and the German word for shark, Hai. The body was designed by Trevor Fiore, of Carozzeria Fissore. A second car was made with a longer wheelbase and minor detail changes like door handles and red bodywork. This car was named the Hai 450 GTS to mark the changes.
Monteverdi initially planned to produce 49 copies, but the production was halted after the two prototypes. This is most likely due to the car's speculated $27,000 USD price tag, a considerable sum for such a car in that era. In the 1990s, two additional replicas from spare parts were made by Monteverdi, that now reside in the official Museum in Basel-Binningen.