manufacture of the RWD "G-Body" Regal, but GM had to extend the build of the Grand National to meet customer demand into December. GNX For the final year, 1987, Buick introduced the limited production GNX, for "Grand National Experimental", at $29,900 ($ in dollars). Made in partnership with McLaren Performance Technologies/ASC, Buick produced only 547 GNs with the interior trim package, that were then sent off to McLaren and upgraded into the Buick GNX. Buick underrated the GNX at at 4400 rpm and a very substantial at 3000 rpm of torque, although actual output is and . This was created to be the "Grand National to end all Grand Nationals". Changes made included a special Garrett AiResearch T-3 turbocharger with a ceramic-impeller blowing through a more efficient and significantly larger capacity intercooler with a "Cermatel (ceramic-aluminum) coated" pipe connecting the intercooler to the engine. A GNX specific EPROM, low-restriction exhaust with dual mufflers, reprogrammed turbo Hydramatic 200-4R transmission with a custom torque converter and transmission cooler, and unique differential cover/Panhard bar included more of the performance modifications. Exterior styling changes include vents located on each front fender, 16 inch black mesh style wheels with VR-speed rated tires, and deletion of the hood and fender emblems. The interior changes of the GNX included a serial number on the dash plaque and a revised instrument cluster providing Stewart-Warner analog gauges, including an analog turbo boost gauge. The GNX used a unique torque arm that was mounted to a special, GNX only, rear differential cover, for increased traction. The torque arm rear suspension alters the suspension geometry, making the body lift while planting the rear tires down, resulting in increased traction. GNX #001 is the 1986 prototype currently owned by Buick and sometimes makes appearances at car shows around the US. Dragstrip performance was measured as faster than the Ferrari F40 and the Porsche 930 with a time of 12.7 seconds at (0.3 and 0.8 seconds quicker, 2.9 and faster) and a 0- time of 4.6 seconds (0.4 and 0.3 seconds quicker, respectively). The stealthy appearance of the all-black GNX and Grand National (and the resemblance of its grill to his helmet's mouthpiece), coupled with the fact that the Grand National was initially released during the popularity of Star Wars movies, earned it the title "Darth Vader's Car". Car and Driver covered the GNX model's introduction with the headline "Lord Vader, your car