Hidden Gems: The Obscure Supercars Based on America’s Favorite Sports Car
When it comes to iconic American sports cars, the Chevrolet Corvette stands at the forefront. Since its debut in 1953, the Corvette has captured the hearts of enthusiasts worldwide with its distinct style and powerful performance. But did you know that beneath some lesser-known supercars lies the DNA of the beloved Corvette? In this article, we uncover five obscure yet breathtaking supercars that share a common platform with America’s favorite sports car.
The Iso Grifo 90
In 1989, Pierro Rivolta, the son of Iso founder Renzo Rivolta, aimed to revive the Iso Grifo, a stunning grand tourer popular in the 1960s and 1970s. To achieve this, Rivolta used a Chevy powertrain just like its predecessor, but this time, it also borrowed a Bowtie chassis – the C4 Corvette. Iso engineers transformed the Corvette into the Iso Grifo 90 by designing a bespoke body and enhancing the suspension with the help of race experts, Dallara.
The Iso Grifo 90 boasted a powerful 5.7-liter, Callaway-tuned LS6 engine producing 490 horsepower. It offered incredible performance, with a claimed 0-60 mph (100 kph) time of 3.6 seconds and a top speed of 186 mph (300 kph). Unfortunately, due to the global financial turmoil at the time, the Grifo 90 remained a prototype and never made it to production. However, a few years later, an Italian brand resurrected the project and manufactured twelve units of the Grifo 90 based on the C5 Z06 ‘Vette.
Callaway Super Speedster LM
Reeves Callaway and his team at Callaway Cars are renowned for their expertise in tuning Corvettes. In the early 1990s, they embarked on an ambitious project to race modified Corvettes at Le Mans, resulting in the creation of the Callaway LM. Based on the C4 ZR-1, the project also birthed a street-legal one-off known as the Callaway Super Speedster LM. Equipped with a heavily tuned suspension and a completely new body designed by Paul Deutschman, the Super Speedster LM was a sight to behold.
Under the hood, the Super Speedster LM housed the ZR-1’s Lotus-designed LT5 V8 engine. With the addition of an insane twin-turbocharged system, the V8 produced a staggering 766 horsepower. This made the Callaway Super Speedster LM not just a supercar but a hypercar decades ahead of its time. Unfortunately, only one unit was built in 1991, and subsequent plans for production were scrapped due to limited demand.
During the 1990s, the Jankel Group, a British coachbuilding firm famous for creating ultra-luxurious versions of renowned brands, faced a decline in demand for their creations. In response, they embarked on a more affordable project, resulting in the development of the Tempest. The Tempest, resembling the C4 Corvette, featured a convertible body hand-built by Jankel. It offered multiple engine options, including the donor Chevy’s standard LT1 V8, a supercharged LT1 version, and a custom, supercharged TRACO unit.
The flagship TRACO V8, rated at 537 horsepower, was built on a four-bolt competition Chevy block with forged internals and a motorsport-derived cylinder head. Around 35 examples of the Tempest were produced between 1991 and 1993, with the majority featuring the potent TRACO V8.
Bertone, a renowned Italian design and coachbuilding company, faced financial challenges in the late 2010s. To revitalize the brand, they brought in Jason Castriota as Director of Design, who conceived an ambitious plan to transform the formidable C6 ZR1 into a true Italian supercar. The project, named Mantide (Italian for mantis), documented the transformation of the ‘Vette through a series of YouTube videos.
The Bertone Mantide retained the ZR1’s stock chassis and powertrain but received a completely new body with dihedral-opening doors and a bespoke interior. Thanks to its superior aerodynamics, the Mantide boasted slightly better performance than the ZR1. However, its high price tag deterred potential buyers, and only one original Mantide was delivered in 2011. Plans for a limited production run were ultimately abandoned, and Bertone later filed for bankruptcy.
Iso’s legacy didn’t end with the Grifo 90. In 2017, the Italian coachbuilder Zagato partnered with Polyphony Digital’s Gran Turismo franchise to bring Iso back to life. The virtual concept, featured in the video game, garnered significant attention and convinced the Rivolta family to revive the brand. Zagato took charge of designing the first modern Iso, resulting in the GTZ (Gran Turismo Zagato).
Inspired by the Grifo-based A3/C race car, the GTZ featured an exquisite Zagato body, hiding a Corvette C7 Z06 underneath. It was powered by a 660-horsepower supercharged 6.2-liter LT4 engine, making it both a powerful and visually striking Italian supercar. With plans to produce only 19 units, the GTZ quickly sold out after its official unveiling in 2021.
These obscure supercars, with their roots in America’s favorite sports car, exemplify the Corvette’s versatility and adaptability. Although some never made it to production or experienced limited success, they remain hidden gems in automotive history. Whether it’s the unique styling of the Iso Grifo 90, the sheer power of the Callaway Super Speedster LM, the British luxury of the Jankel Tempest, the audacity of the Bertone Mantide, or the modern revival of Iso in the GTZ, these supercars remind us of the Corvette’s lasting impact on the world of high-performance automobiles.