The 1987 Buick GNX is the rare modern collector car whose value is decided by hardware and paperwork rather than its VIN. Buick and ASC/McLaren converted 547 black Grand Nationals into GNXs, and the market now treats mileage and originality as the whole story: the same 30-mile car sold for $200,000 in 2024 and $427,000 in September 2026. These Buick GNX specs cover production, drivetrain, identification, weak points and value, so you can separate a documented car from a Grand National wearing the right parts.

Rear view of a black 1987 Buick GNX showing its rear bumper and exhaust — Photo: ilikewaffles11 / Wikimedia Commons, CC BY 2.0.

Buick GNX specs at a glance

Item	Detail
Model	1987 Buick Regal GNX (“Grand National Experimental”), rear-drive G-body coupe
Production	547 cars, all black, built for one model year
Converted by	Buick with ASC/McLaren (McLaren Performance Technologies), starting from a Grand National with the interior trim package
Engine	3.8-liter (231 cu in) turbocharged V6, sequential fuel injection, Garrett T-3 turbo with ceramic impeller, larger intercooler
Output	Rated 276 hp at 4,400 rpm and 360 lb-ft at 3,000 rpm; commonly cited as roughly 300 hp and 420 lb-ft in reality
Transmission	Reprogrammed 200-4R four-speed automatic with a custom torque converter and cooler
Rear end	GNX-specific torque arm, Panhard rod and differential cover
Wheels and tires	16-inch black mesh aluminum wheels; Goodyear Eagle VR-rated tires, 245/50 front and 255/50 rear
Performance	0–60 mph in 4.7 seconds and the quarter mile in 13.5 seconds (Car and Driver, 1987)
Original price	$29,290 on a documented window sticker; some sources cite $29,900
Auction record	$427,000, Bring a Trailer, September 2026 (No. 450, 30 miles)

Production totals

Buick built 547 GNXs in 1987, all in black. Reporting on the record sale notes that Buick had planned for roughly 500 cars before the final count reached 547. Each car began life as a regular Grand National, of which 1987 production reached about 20,193, so the GNX is under three percent of its own model year.

The numbering matters more than the total. Every GNX carries a sequential plaque on the dash, and the last car, No. 547, sold at Mecum Kissimmee in 2017 with 68 miles. A 1986 prototype is reported to wear No. 001 and remain with Buick. For the wider auction record, see our 10 most expensive Buick GNXs ever sold at auction.

Engine and drivetrain

The GNX started with the Grand National’s turbocharged 3.8-liter V6, which Buick rated at 245 hp and 355 lb-ft in 1986. McLaren and ASC added a Garrett T-3 turbocharger with a ceramic impeller, a larger intercooler, a Cermatel-coated charge pipe, a GNX-specific engine program and a low-restriction dual-muffler exhaust. Buick’s published figures were 276 hp and 360 lb-ft, widely believed to understate the real output of about 300 hp and 420 lb-ft.

Power goes through a 200-4R four-speed automatic with revised programming, a custom torque converter and a transmission cooler. At the rear, a unique torque arm, a Panhard rod and a GNX differential cover changed the geometry to plant the tires under hard launches. Car and Driver measured 0–60 mph in 4.7 seconds in 1987.

Engine bay of a 1987 Buick Regal Grand National with the Garrett turbocharger visible on the 3.8-liter V6 — The Grand National engine bay that the GNX program started from. Photo: BUTTON74 / Wikimedia Commons, CC BY-SA 4.0.

Special options and equipment

The GNX was sold as a single, fully equipped configuration, so there is no options list to decode. The meaningful “options” are the GNX-specific parts and the factory-installed comfort equipment that came with every car.

GNX-specific hardware: turbo, intercooler, engine program, exhaust, torque arm, Panhard rod and differential cover.
Wheels and tires: 16-inch black mesh wheels with GNX center caps and Eagle VR-rated rubber.
Interior: revised instrument cluster with analog gauges, including a turbo boost gauge, and the numbered dash plaque.

Standard equipment: air conditioning, power windows and locks, cruise control, tilt steering column, six-way power driver seat and an upgraded stereo with equalizer.
Costs: the GNX carried a $650 gas guzzler tax on its window sticker, and the GNX conversion alone was priced at $10,995 over a Grand National.

Identifying details

Start with the dash plaque and work outward. A genuine GNX should show the following, and each item should agree with the paperwork.

Black paint only; no other color was offered.
Functional louvers in the front fenders, and deleted hood and fender emblems.
Black mesh wheels with GNX center caps.
GNX-only rear differential cover, torque arm and Panhard rod.
A numbered dash plaque reading from 1 to 547, matched to the build paperwork and any registry record.

Do not treat the VIN as proof. GNX and standard Grand National VINs share the same pattern (1G4GJ117…HP4…), so the number confirms a 1987 Regal Grand National and little else. The same lesson applies across the hobby, as in our guides to the 1969 Camaro Z/28 DZ engine pad and the 1964–65 Pontiac GTO PHS paperwork: the proof sits in documents and date-correct hardware.

Common weaknesses

Sources agree on a short list of cosmetic and condition issues, plus one structural caution for the market: most Grand Nationals have been modified over four decades, so originality is the first thing to verify.

Cracked dash pads and worn driver seat bolsters, the two most commonly reported cosmetic wear points.
Modified or swapped turbo, intercooler, engine program or fuel system. Compare each against the factory GNX specification.

Cars that sat for years: check fluids, hoses, belts, tires and the fuel system rather than assuming low mileage means ready to drive.
Clones and mismatched parts: a standard Grand National fitted with GNX parts is worth a fraction of a documented car.
Unverified mileage: at these prices, odometer and service history are worth independent confirmation.

Current value range

Condition and mileage drive everything. A summary of Hagerty’s guide published in 2025 listed about $110,000 for a #3 (good) car and about $257,000 for #1 (concours), and auction results have since moved well above that. The latest benchmark, from Classic.com, sits near $191,000 for the model in 2026.

Item	Detail
Record sale	$427,000, Bring a Trailer, September 2026, No. 450, 30 miles (the same car sold for $200,000 at 26 miles in June 2024)
Prior record	$308,000, Barrett-Jackson Scottsdale, January 2022, 568 miles
Sub-1,000-mile cars	$255,000 (843 miles, August 2025) up to $275,000 (8.9 miles, Barrett-Jackson Las Vegas, June 2021)
Low-to-moderate mileage	$215,000 to $243,096 (1,200 miles, 2021 and December 2025); $230,000 (2,200 miles, Bring a Trailer, May 2025); $225,000 (8,000 miles, July 2026)
Floor	About $90,500 reported in 2022; modified or undocumented cars trade materially below the figures above
Context: standard Grand National	Hagerty #3 near $36,900 (January 2025); original low-mile cars have sold in the $75,000–$79,000 range

Interpretation, not fact: a documented, lower-mileage GNX in the roughly $190,000–$250,000 band looks like the working market, with sub-1,000-mile cars commanding a premium and the $427,000 sale as a time-capsule outlier rather than a new baseline. The same car adding $227,000 in value for four additional miles shows buyers are now paying for the odometer.

What separates a good Buick GNX from an average one

Verified mileage. Single- and low-double-digit cars sit in a separate market from 1,000- to 10,000-mile cars.

Plaque, hardware and paperwork that agree. The dash number, GNX differential cover, torque arm and Panhard rod should match the build documentation and, ideally, the registry.
Original drivetrain components. Factory turbo, intercooler, engine program and exhaust, with receipts for any replacement.
Window sticker and early ownership records. The original window sticker is the cleanest proof of how the car left the dealer.

Interior without the usual wear. An uncracked dash pad and unworn driver bolster are harder to repair invisibly than a mechanical fix.
Original-finish paint and trim. Black paint shows every repair, so correct panel gaps and consistent finish matter.

Interior of a 1987 Buick Regal Grand National with dash and gauges — The Grand National cabin the GNX was built on; GNX cars add a numbered dash plaque and revised gauges. Photo: Eric Friedebach / Wikimedia Commons, CC BY 2.0.

Average GNX examples pass the first three checks and fail the others; the best cars pass all six. For a live example of how a numbered car is presented at sale, read about GNX No. 461 at Vicari’s Biloxi sale.