A cola is a cola is a cola, most of the time.
The "cola" flavor—sugar, vanilla, cinnamon, acid, a little citrus—is so deeply impressed on the American palate that we hardly recognize it for its parts anymore. It's the soft-drink generic, like tap water or salt-and-peppered scrambled eggs. One can do exciting things with cola—see, for example, the smoked cola at Nashville's Patterson House—and, sure, a Coke hits the spot now and then, but the stuff offers little potential for surprise.
After plenty of generic, too-sweet disappointments, I've begun to regard the word "cola" as a cue to move on down the soda aisle. Last week in Tennessee, though, I tried a soda that broadened my sense of what a cola can be.
Red Rock Cola, from the soda-soaked metropolis of Atlanta, Georgia, is vanilla-rich and fizzy, with some of the caustic, tooth-rotting acidity we've come to expect from brown soda, but not quite the syrupy base; it is thinner than your typical soda-fountain cola, a trait I've noticed in a number of old-formula sodas sweetened with cane sugar instead of high-fructose corn syrup.
Underpinning the cola flavor is a watery base of cold glass and metal that best distinguishes Red Rock from the competition. That flavor is not entirely unique to this cola—I've tasted it in Blenheim Ginger Ale and, to a lesser extent, in Mexican Coca-Cola and other glass-bottled, sugar-sweetened drinks—but it is especially prominent here. This flavor does not blend with the vanilla and sugar, but works alongside them, giving this soda a layered complexity that is a direct refutation of the idea that cola can't be exciting.