The Buick Grand National GNX is technically a variation of the Buick Regal, the mid-sized car that Buick introduced for the 1973 model year. The Buick Grand National made its debut in February 1982. It earned its name for the NASCAR Winston Cup Grand National Series, which the automaker won in 1981 and 1982. At first, there were only going to be 100 units of the Grand National, although Cars and Concepts also retrofitted 215 Regals to meet the description. It featured a naturally-aspirated 4.1-liter V6 with 125 horsepower, with at least 35 models featuring a turbocharged V6.
The Grand National disappeared for 1983, returning in 1984 in all black with a turbocharged 3.8-liter as standard. The engine was modified for 1986, including air-air intercooling to boost performance up to 235 horsepower.
The 1987 Grand National GNX
For the final year of the Grand National lineup, Buick also produced the GNX, which stood for Grand National Experimental. At release, it cost $29,900, and it was created as part of a partnership between McLaren Performance Technologies/ASC and Buick. In total, Buick produced 547 GNs with the appropriate interior package. From there, McLaren upgraded these autos to GNX models. The GNX was supposed to be the “Grand National to end all Grand Nationals.”
The Buick Grand National GNX was underrated to produce 276 horsepower at 4,400 rpm along with 360 pound-feet at 3,000 rpm. In reality, experts agreed that it produced 300 bhp and 420 pound-feet. To further enhance the performance, the GNX saw a number of enhancements, such as a T-3 turbocharger from Garrett AiResearch featuring a ceramic-impeller that blew through an intercooler with a larger capacity and was more efficient. This intercooler had a Cermatel-coated pipe that connected the engine and the intercooler.
There was also an E-EPROM specific to the GNX, reprogrammed turbo Hydramatic 200-4R gearbox featuring a custom transmission cooler and torque converter, low-restriction exhaust complete with dual mufflers, and a unique Panhard bar/differential cover. This special rear differential cover also featured a unique torque arm that delivered increase traction by altering suspension geometry. The result was that the GNX was able to complete a quarter-mile in 12.7 seconds at 113.1 miles per hour. It also could go from 0 to 60 in 4.6 seconds. These figures made the Grand National GNX faster than both the Porsche 930 and Ferrari F40.
The exterior of the GNX stood out from other Grand Nationals with its vents on each of the front fenders. It also lacked fender or hood emblems and featured 16-inch black mesh-style wheels that featured VR-speed rated tires. Inside, the GNX had a dash plaque with a serial number plus a revision to the instrument cluster that featured an analog turbo boost gauge and other Stewart-Warner analog gauges. The dark exterior of the GNX, as well as the fact that the Grand National release took place when “Star Wars” was popular, meant that these vehicles were sometimes referred to as “Darth Vader’s car.”