It's an old auto industry cliche -- "you can't sell a young man an old man's car, but you can sell an old man a young man's car." It's also true. The sporty Mustang was a young man's -- and woman's -- car. The under-30 crowd loved it. But older people also bought them, often as a second car. The Mustang hit a sweet spot in the market, appealing to a wide range of buyers.