The black label Coke Zero uses aspartame instead of saccharine, is strongly carbonated, and has a noticeable caffeine bite. Sorta similar to Barq's root beer, which is less flavorful than A&W and other competitors but has caffeine and was marketed with "Barq's has bite."
The newer version tastes a lot more like regular coke, but to get that flavor, it seems that it is meant to be poured over ice.
The newer version tastes a lot more like regular coke, but to get that flavor, it seems that it is meant to be poured over ice.