This one-of-a-kind 1991 G4R Series Greenwood prototype was handcrafted by 1970s racer John Greenwood. It is one of only three such C4 prototypes built, and the only one personally certified by Greenwood. The complete and fully functional body package includes the G4R super wing, a twin-nostril high-rise hood, hood louvers, a window fairing, front spoiler, rocker-panel extensions, and a completely revised rear bumper. In addition to these stylistic elements, the induction system was improved by a K&N ram-air induction system, and twin Phazer radar-jamming transmitters are molded into the front and rear bumpers.

SCM Analysis


Vehicle:1991 Greenwood G4R Body Kit Prototype
Years Produced:1991
Number Produced:3 (G4R prototypes)/14,967 1991 coupes/20,639 all 1991
Original List Price:$32,455 (base) + approx. $15,000 in Greenwood body mods
SCM Valuation:$16,430 on this day
Tune Up Cost:$150
Distributor Caps:$12
Chassis Number Location:Driver’s side dash at windshield
Engine Number Location:Lower rear side of crankcase
Club Info:Corvette Club of America
Alternatives:1988–89 Corvette Challenge Racer; 1991–92 Callaway Corvette; 1992 Lingenfelter Corvette
Investment Grade:D

This car sold for $16,430, including buyer’s premium, at Mecum’s Kissimmee High Performance Auction in Kissimmee, Florida, on January 31, 2010.

John Greenwood is best known for his stunning, world-beating IMSA Corvette road racers that thrust onto the world stage in 1974. Introduced at a ten-lap sprint race at Road Atlanta that year, the cars would eventually win the ’74 championship before taking other major victories in the following years. The aerodynamic improvements introduced on the Greenwood Corvettes were soon copied by others, including by Porsche on their highly successful 935s, which also dominated IMSA for a half-decade.

Greenwood’s success led to the building of race cars for privateer drivers, some of whom also did well in IMSA and SCCA during the mid-1970s. Soon others who liked the cars’ wild styling but had no intention of racing began clamoring for a street-legal Greenwood Corvette as well. Aware of the possibilities for performance-tuned Corvettes (thanks in part to the serious power deficits then imposed by both the California Air Resources Board and the federal government), Greenwood introduced his first wide-body C3, known as the “Batmobile,” at Cobo Hall in Detroit, Michigan, in 1974.

Greenwood’s angle in proffering street-legal cars was really to amortize the cost of specialty tooling that would ultimately help his team win races. Initially the custom street cars were built with only aerodynamic and styling improvements, but engine and chassis tuning eventually entered the formula. With several different levels of aero and drivetrain modifications available to them, Corvette enthusiasts with enough patience and an open wallet could have a street-legal vehicle configured as a convincing Greenwood racer-replica.

A low production run of high-powered cars

From 1975 until 1981, Greenwood built 43 custom street cars based on five distinct body styles. The last three styles—the Turbo GT, Daytona, and GTO—all used turbocharged small-block engines. While racing has always been full of imitation, now Greenwood’s street cars were also being copied, with the most well-known clone produced by Eckler’s of Florida. While the copycats appeared similar in form, Greenwood’s engineering was not even attempted by such wannabes, who tried to capitalize on his racetrack fame.

Just as the third-generation Corvette left room for improvement, so did the fourth—and upon its release in early 1983, a slew of Corvette tuners eagerly jumped on the aftermarket bandwagon. John and brother Burt Greenwood were no different in this respect, yet their years of experience in building 700-horsepower racing machines (and the chassis and aerodynamic engineering that went into them) told them that in order to make the perfect street car, they would have to start from scratch.

Although the C4 was already an entirely new car inside, outside, and underneath, in GM’s rush to produce it, some congenital defects remained. Intent on perfecting the platform, Greenwood spent more than a few years and hundreds of thousands of dollars fixing these perceived flaws. But when he finally brought the performance-tuned G-350 and G-383 models to market, few takers were to be found. Ultimately, he came to the conclusion that his new creations needed more reconfiguring to sell at a reasonable price.

Another problem for Greenwood at the time was the competition. Callaway Cars had grown a reputation for both performance and appearance, and they even had the distinction of a potent Twin-Turbo option commanding its very own RPO B2K in the official Chevrolet order book for an impressive five years.

A body kit does not a performance car make

Regarding the car sold by Mecum in Kissimmee (offered one lot before another Greenwood car, our C5 profile on p. 28), it was not one of Greenwood’s performance-tuned cars but a prototype of what was to become the G4R cosmetic body kit. Although certified as authentic by Greenwood, today it is special only to those who appreciate the time and trouble the man took on his quest to improve the C4.

Close examination of this particular example reveals that it has not exactly spent its life in protective bubble wrap. Instead, the car has been tastelessly modified with a set of (likely aftermarket) chromed C5 Z06-style alloy wheels, a Borla (or similar)aftermarket exhaust system, a garden-variety Accel ignition coil, and the meaningless boy-racer application of red paint to valvetrain and throttle-body covers—most likely done as it is a well-known fact that red paint results in instant and palpable performance gains. On the bright side, the white body color is one of the more complimentary colors for the C4’s shape.

Despite the racy body parts, a rumbling exhaust note, and the appearance of sitting lower on its haunches than the run-of-the-mill period Corvette, this car offers no more performance than stock, and thus has to frighten (or impress, take your choice) onlookers by stance alone. At auction, the math didn’t work—because there is little reason to pay much extra for what’s basically a body kit poured over a stock L98 240-horsepower, automatic-transmission 1991 Corvette. At the end of the day, guys who target muscular-looking cars also want the muscle to go with it.

Given the dated nature of this styling kit, I’d have to say this sale was market-correct, if not slightly well-sold. The market appeal of a 1980s supercar silhouette Corvette is not likely to come back into vogue in the foreseeable future

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