GM has been mismanaged since the late 50's. The only reasons they didn't tank years ago are the American motivation to buy American cars (despite the lack of quality and engineering) and the fact that until the early 80's they had an effective market monopoly. Once these giants started to experience competition from European and Japanese auto makers in the 80's they sank their research dollars into making the same cars for less cost. While this is an important thing to do, they completely neglected the fact they were selling a product that was losing it's competitive advantage due to stagnation.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine