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The Zagato company took a C7 Corvette Z06 and transformed it into the IsoRivolta GTZ, a "spiritual descendant" of the Iso Grifo A3/C (Corsa).  The original A3/C race car was developed by Giotto Bizzarrini not long after he left Ferrari, where he had served as cheif engineer behind the 250 GTO, which is revered as the world's most expensive car.  Bizzarrini purportedly fancied the A3/C as his "own personal evolution of (and improvement upon) the GTO design."
The major differences between the 1980 and 1982 Daytona and the 1981 GTO are the hood, the tops of the rear fenders, and the rear spoiler/bumper cover. The Daytona had an elaborate, short vertical fin on top of the rear fender that turned several turns “in and back,” flowing to the wide, long, table-like rear spoiler. The GTO’s rear fenders pontoons are the same as.
The Duntov Turbo was built as a partnership between American Custom Industries (ACI), a company known for building replacement Corvette body panels, and Zora Arkus-Duntov. It was developed as a highly-stylized convertible sports car based on the production model Corvette. Each of the special Duntov Turbo's also came with a turbocharged V8.