One of the least predictable things about this year’s big game was the buzz created by the halftime show special guest appearance of the 38-year-old limited edition speed demon known as the Buick GNX.

Sold briefly in 1987, the GNX had a limited run – Buick only built 547 of them, with the help of Michigan-based companies ASC Inc. and McLaren Engines. The GNX was a revved-up Buick Grand National, itself a performance edition of the mid-sized Regal.

The GNX – the acronym stands for Grand National Experimental – turned the already sporty Grand National into a studly supercar, adding a Garrett AiResearch T-3 turbocharger, dual mufflers, a turbo Hydromatic 200-4R transmission and various other tweaks and upgrades.

While sticking to the all-black exterior of the Grand National – not for nothing was it known as “Darth Vader” – Buick tweaked the look for the GNX, adding 16-inch black mesh aluminum alloy wheels and removing the Regal’s hood emblem. And every GNX got a serial number on a dash plaque – GNX #001 resides in the GM Heritage collection.

The original MSRP for the GNX was $29,290, which, as Buick noted at launch, compared to $18,295 for a “heavily equipped” Regal Grand National. But if you could in fact find one, you’d almost certainly pay well into the six figures for a GNX now.

In a decade in which the world embraced the econobox, the GNX was a fire-breathing throwback – the ultimate American muscle car.

The Grand National was developed while Buick was led by Lloyd Reuss, former GM president and the father of current GM President Mark Reuss. Lloyd had moved on to lead GM North American automotive operations by the time the GNX was under development, but Mark worked on the project.

“I joined GM in 1986, and my first job was powertrain integration development engineer for Buick,” Reuss recalls. “The first winter I was with the company, I rented an apartment in Chandler, Arizona. Our proving grounds were nearby in Mesa. I loved working for Buick then – my dad had been the general manager, and Buick had really great cars with really great engines, including the Regal Grand National.”

Reuss was involved in the early development of the souped-up version of the Grand National that came to be known as the GNX.

“In Arizona, we had a Grand National we were using as a surrogate for the GNX, which was under development, with the right tires and other mods,” he says. “Now, this was not my official job, but… one of our electronic techs at Mesa was a good friend named [James] “Gabe” Poplawski, a long-haired, Harley-ridin’ dude – this was a different time in my life when I was single and rode a Harley.”

Reuss says he and Poplawski spent considerable time on the project.

“Gabe was doing after-hours stuff at Firebird International Raceway, a drag strip in Phoenix,” Reuss says. “And he and I took that Grand National/GNX surrogate out there quite often, and we would play with the calibration until we got the best times. And the best times came when we used what Gabe called ‘the grenade chip,’ because we were afraid if we ran it full throttle for too long with that chip, the engine would blow.”

That work contributed to the short-run production of the GNX.

“I have a lot of great memories about that experience,” Reuss says. “Gabe was a super brilliant guy. Before we scrapped that car, he took the driver’s seat out of it, and, many years later, he sent it to me at the RenCen. It’s not a beautiful seat, but it’s a Grand National seat that was in the development car for the GNX. And it’s in my office.”

Reuss gives credit to his father for laying the groundwork for the project.

“My dad was gone from Buick by the time the GNX went to production, but if he hadn’t previously given the green light to the Grand National, there would have been no GNX,” he says. “He had a saying about the Grand Nationals: ‘Fast With Class.’ And I think that’s why Grand National, and especially GNX, resonated with customers back then, and why it still does today as strongly as ever – because it’s so fast. It would beat Corvettes, Ferraris, all the exotics – it was the fastest car on the road in America.”

And, Reuss adds, the GNX can still hold its own.

“When you drive one, even now, it’s frighteningly fast from 0-60,” he says. “But it isn’t bad at all, ride and handling-wise – it still rides like a Buick. You can drive it all day on the highway. It’s very nice to drive… all the comforts, like air conditioning, T-tops, concert sound, power seats, power antenna if you remember those… it was a fully loaded Buick. But brutal. In the best way.”