Merchandise 7X-100

The cola wars of the late 20th century were waged with as much strategy, secrecy, and technology as many conventional wars. When Coke was threatened by the Pepsi Challenge, they responded ten years later with Merchandise 7X-100, which we came to know as New Coke. It was the first major formula change since 1903, when cocaine was taken out of the recipe. Although tests showed that people liked the taste of New Coke, the product fell flat on its face. The original Coke formula, new relabeled Coke Classic, returned to the shelves only 79 days after New Coke was introduced.

Coca-Cola then became, and has since remained, the most profitable soft drink in the world. The "marketing blunder of the century" was so successful, in fact, that some people are convinced that New Coke Was an Inside Job– a delicately engineered gambit to revitalize the brand. As Coca-Cola president Donald Keough put it, "Some critics will say Coca-Cola made a marketing mistake. Some cynics will say we planned the whole thing. The truth is we are not that dumb and we are not that smart." Coca-Cola truthers have also suggested that New Coke was a disposable facade intended to mask the transition from sugar to HFCS.

There are several psychological explanations for the failure of New Coke, which are explored in this article at Damn Interesting. Link