This 1987 Buick GNX is #454 of 547 produced for a single model year and is powered by a turbocharged 3.8-liter V6 paired with a four-speed automatic transmission and a limited-slip differential.
The 3.8-liter V6 was modified by ASC/McLaren with a Garrett T3 turbocharger under a heat shield with GNX lettering along with a larger air-to-air intercooler and a low-restriction exhaust system.
Factory-rated output was 276 horsepower and 360 lb-ft of torque.
The fuel pump was replaced in March 2023.
Power is sent to the rear wheels through a Turbo-Hydramatic 200R4 four-speed automatic transmission with a factory-upgraded oil cooler and a limited-slip differential that features a GNX-branded aluminum rear cover.
The Grand National Experimental was created in partnership with McLaren Performance Technologies/ASC to celebrate the end of the vehicle’s production run, and all 547 examples were finished in black.
Cosmetic details specific to the GNX include heat-extracting fender vents, composite wheel arch flares, a three-piece rear spoiler, and GNX badging.
Additional exterior details include an automatic power antenna, a rear window defogger, sport mirrors, and dual exhaust outlets.
Factory 16″ cross-lace wheels feature GNX-branded center caps along with polished lips and are wrapped in 245/50 BFGoodrich g-Force Comp 2 tires.
The GNX features front suspension components from the contemporary Grand National, and upgraded rear components include a Panhard rod, a torque arm, and an additional frame cross member.
Braking is handled by power-assisted front discs and rear drums.
The cabin features front bucket seats and a rear bench upholstered in black and Sand Gray cloth with Turbo 6 embroidery on the front seat headrests.
Additional amenities include a power-adjustable driver’s seat, air conditioning, cruise control, power windows, and a Delco AM/FM/cassette stereo with a graphic equalizer.
A plaque mounted to the passenger side of the dashboard identifies this car as GNX #454.
The three-spoke leather-wrapped steering wheel fronts GNX-specific Stewart-Warner instrumentation consisting of a 160-mph speedometer, an 8k-rpm tachometer, and gauges for boost, oil pressure, coolant temperature, and fuel level.
The five-digit mechanical odometer shows 13k miles.
