In the haze of underwhelming American cars of the 1980s, Buick—a brand long associated with elderly buyers and soft luxury—did something unthinkable. It unleashed a pair of performance monsters that tore through quarter miles and took down Corvettes, Mustangs, and even European sports cars. These were the Buick Grand National and the ultra-rare, legendary GNX (1987 GNX in lead photo).