Diet Coke
Diet Coke does not use a modified form of the Coca-Cola recipe, but instead an entirely different formula. The controversial New Coke, introduced in 1985, used a version of the Diet Coke recipe that contained high fructose corn syrup and had a slightly different balance of ingredients. In 2004, Coca-Cola introduced Coca-Cola C2, which it claims tastes much closer to Coca-Cola but contains half the carbohydrates. In 2005, the company introduced Coca-Cola Zero (replaced by "Coca-Cola Zero Sugar" in 2017), a sugar-free variation of regular Coca-Cola.
New Coke
By 1985, Coca-Cola had been losing market share to diet soft drinks and non-cola beverages for many years. Consumers who were purchasing regular colas seemed to prefer the sweeter taste of rival Pepsi-Cola, as Coca-Cola learned in conducting blind taste tests. However, the American public's reaction to the change was negative, even hostile, and the "New Coke" was considered a major failure. The company reintroduced Coke's original formula within three months of New Coke's debut, rebranded as "Coca-Cola Classic", and this resulted in a significant gain in sales. This led to speculation by some that the introduction of the New Coke formula was just a marketing ploy to stimulate sales of original Coca-Cola; however, the company has maintained that it was a genuine attempt to replace the original product.