1964 (1/2): Ford Mustang
The small Falcon was Ford's least interesting car back in the early Sixties. It was an entry-level lump for people who couldn't afford a real Ford. But re-wrap the Falcon's structure and mechanical bits under crisp sheetmetal, liberally decorate the result with plastic running horses and the result was an instant legend, the Mustang. Yes, the Mustang looked great, but what really set it apart was how Ford marketed it as a car for young people born after World War II. This is the product that has defined youth culture and America's obsession with cars for more than 50 years.
What it's uniquely American: Over head, kids aren't just kids, they're consumers.