With its rare production models, classic racers and intriguing concept cars, the National Corvette Museum in Bowling Green, Kentucky, can awe even casual car buffs. Indeed, amidst all that automotive flash, a seemingly normal plain white model on display from the car’s fourth design generation—“C4” to the Corvette cognoscenti—might not raise a pulse.

But it sure raises eyebrows.

This C4 is anything but normal. It’s a 1983 Chevrolet Corvette, highly unusual since there was no Corvette for the 1983 model year. For its 30 anniversary, America’s longest-running sports car—the one designed to flaunt U.S. speed, power and ingenuity in a class traditionally dominated by European entries—took a somewhat mysterious gap year.

But why?

Initially planned as a 1982 model, the fourth-gen Corvette, by far the most advanced to that time, was first pushed back to a fall 1982 introduction as a 1983 model—and then again to spring 1983 as ambitious upgrades met with further delays. By then, Chevrolet had decided to designate the “1983” Corvette a 1984.

The museum’s white car is, however, a genuine 1983 Corvette, the only one in the world. How did that happen? Built on June 28, 1982, it was the fourth of 43 “pilot assembly” cars made to validate production processes and for other engineering, testing and training purposes. Common industry practice calls for crushing such vehicles when such work is completed, since they cannot be sold to the public.

Forty-two of the C4 pilot cars met that fate, but one, identified as RBV098, slipped through. In 1984, a new plant manager found it parked outside, neglected. He had it cleaned up and put on display. It also got an American flag motif paint job, later changed back to the original solid white. When the museum opened in 1994, General Motors loaned RBV098 for display and eventually donated it. RBV098 now stands as a unicorn, an artifact of one of Corvette’s most sweeping upgrades ever.

For Corvette, the 1983 model year turned out to be more of a “leap year” than a gap year. With extraordinary strides made in chassis engineering, aerodynamic design and overall performance, the C4 seemed a decade ahead of the C3 it replaced. And that’s an understatement.

Introduced for 1968, the C3 was essentially a redesigned body and interior on the C2 Sting Ray chassis, which dated back to 1963. A dream car for many, the C3 Corvette drove plenty of sales for parent company General Motors through the 1970s. But that third generation left a different impression on some diehard enthusiasts. The primitive exhaust-emissions technology of the late 70s and early 80s—think old-school carburetors and distributors—dulled performance. Added safety features bloated the car’s weight. And while 1960s and ’70s Corvettes could still impress with power and speed, they often came up short in handling precision, ride comfort, general refinement and build quality. In its road test of a ’79 model, Car & Driver magazine suggested, “The time has come to pass the crossed flags on to the next generation.”

The C4 was designed to be more competitive in those areas with premium European sports cars. And at Chevrolet, that transition was already getting underway.

GM’s commitment to the fourth-gen Corvette included building a much-needed new assembly plant in Bowling Green to replace the 1920s-vintage St. Louis factory that had made Corvettes since 1953. Located a mile from where the Museum would later be built, the plant was ready in summer 1981—but the new Corvette was not.

A slew of new engineering advances delayed C4 development, meaning that the C3 would live another year, built in the new plant. The 1982 Corvette debuted features destined for the C4, including not-impressive-as-it-sounds Cross-Fire fuel injection for the proven 5.7-liter V-8 engine, along with GM’s new four-speed automatic transmission. The 1982 Collector Edition Corvette also gained a one-piece glass hatchback, which all C4s would get.

The rest of the C4 would be all-new. Engineers still used fiberglass for the body and steel for the frame. While the body style instantly said “Corvette,” the frame was far more exotic than the C2/C3 chassis, and it likely caused the biggest delay in the C4’s gestation.

The C4 was originally designed to use t-tops, two-piece removable roof panels split by a central bar joining the windshield to the rear roof structure, as on the C3. With development well along, Chevrolet General Manager Lloyd Reuss decided the roof should be a one-piece removable panel, as on the Porsche 911 Targa and also the Ferrari 308 GTS seen shrieking across TV screens every week on “Magnum P.I.”

Re-engineering the frame to accommodate the one-piece roof reportedly took nearly a year. Taller side rails were needed to add chassis strength that had been lost with the t-bar’s deletion, creating higher doorsills that made climbing into and out of the Corvette more difficult.

The C4 was definitely a game-changer. Its body, 8.5 inches shorter than the C3, sported fewer curves to improve aerodynamics. The wheelbase (2 inches shorter) enhanced the car’s agility, while the body (2 inches wider) added interior room. The C4 also weighed in about 150 pounds lighter than the C3, which boosted performance.

Opening the huge, one-piece “clamshell” hood, which integrated the fender tops, revealed an engine compartment as finely detailed as any from Europe.

Beneath, the chassis used transverse (sideways) fiberglass single-leaf springs front and rear. This unusual choice proved highly effective and would also be used on the C5, C6 and C7 Corvettes. With standard Goodyear Eagle VR50 “gatorback” tires on 16-inch wheels, the Corvette posted staggering 0.90-g cornering performance, which Car & Driver magazine noted was a world-best.

Car & Driver also noted that the Corvette’s sub-7-second 0-to-60 m.p.h. acceleration and 140-m.p.h. top speed put it among the world’s six fastest production cars at the time. The magazine concluded: “The Corvette is a truly stout automobile. It is all that the fevered acolytes so desperately wanted their fiberglass fossil to be—a true-born, world-class sports car loaded with technical sophistication.”

Other media were likewise enthralled. Motor Trend named the 1984 Corvette “Car of the Year.”

There were complaints, though. The new “4+3” transmission, a 4-speed manual that automatically engaged an overdrive on the top three gears to reduce fuel consumption, was a clunky operator. Most customers stuck with the standard automatic.

The optional Z51 Special Performance Handling Package gave the Corvette astounding agility at the cost of a bone-rattling ride; the digital dashboard was entertaining in a “Knight Rider” way, but was hard to read in sunlight. And as with earlier Corvettes, there were some creaks and rattles.

Still, the 1984 Vette (MSRP at the time: $21,800) was a huge success, with 51,547 built over an extended 18-month model year. (Corvette’s record sales year remains 1979, when 53,807 were sold.) The C4 would go on to have a 13 model-year lifespan, with Chevy issuing a steady stream of significant upgrades along the way, including the ZR1 and Grand Sport high-performance versions. Not bad for a car that missed its initial birthday by almost a year.