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
Coca-Cola's senior executives commissioned a secret project headed by marketing vice president Sergio Zyman and Coca-Cola USA president Brian Dyson to create a new flavor for Coke. The effort, Project Kansas, took its name from a photo of Kansas journalist William Allen White drinking a Coke; the image had been used extensively in Coca-Cola advertising and hung on several executives' walls.