Well first off i dont consider Chows GN to be a GN, it doesnt have the original powertrain.
anyways, yes, the GNX was a legend. It was the final push of the grand nationals and the t-types and it was the last true "muscle car" made. What Buick did was send 547 of their grand nationals to AC McClaren (sp?) and they were worked over. In addition to the motor, fender flares, louvers, different wheels, GNX badging, and a number plat on the dash were added. After their rebirth they rolled out with 310 hp and 310 lb/ft. Capable of a flat 13 second quarter mile they were faster than the corvette of the same year making it the fastest production car in 1987. These 547 monsters were dubbed the GNX, or Grand National eXperimental. The project was cut short though do to both lost revenue because they were faster than the vette and much cheaper, and this is right when the fuel economy issue came to light. After the 547th GNX was returned to the GM plant from McClaren, it was checked over, washed, and driven out to the lot to be shipped out to the dealership. The GNX project was terminated and the assembly line for the last muscle car ever was shut down.
This is my dream car...actually any nice grand national is my dream car...i actually bought this game...just for this car...its sad...i know...call it an addiction.
oh, and as far as the color, there were a couple...for the T-Types. The actual Grand Nationals, and the GNXs came only in black. Reminds me when Henry Ford once said; "You can get a Model T in any color...as long as its black". People get the T-Types and the GNs confused.