Harley Earl's declarations, written over fifty nine years ago and shown below, points to the heart of the matter on why General Motors lost 29 big points of market share over a 27 year period [[1982 to 2009) and ultimately went bankrupt. Now that GM is in it's rebirth, hopefully they will regain a winning status.
Earl was a great champion of diversifying his company away from building large cars, and he and others had originally planned to take this company down a much more harmonic path going into the 1960s...building millions of small cars to meet the demand of the market place. Putting it mildly though, Earl [[being a long winning quarterback inside GM with his team) had a formidable collision with opposites and this battle ultimately cost him his career. In any event, this pioneer's remarkably clear vision is seen in this March 1950 GM Folks magazine article; circulation exceeded 480,000 copies.

More here http://www.carofthecentury.com/answer_to_gm's_market_share_plunge.htm