I Tried And Ranked The Diet Coke At 8 Fast Food Chains

Any aficionado of fast food sodas knows there are good spots and bad spots to order a Diet Coke: some just taste better or worse than others. Some have "the good ice," the pebbly sort that adds a je ne sais quoi to any beverage it graces. Others may have better filtration systems for carbonation, or receive their sodas in packaging superior at retaining the syrup's flavor. Whatever the reason for these differences in taste from one fast food spot to another, I wanted to try Diet Coke at as many chains as I could.

I've already ranked all the most popular diet sodas and felt this was a perfect addendum to that experiment. I've also been a fast-food Diet Coke drinker for years. I used to straight-up pull into drive-thrus just for the joy of being handed a cold Diet Coke and nothing else. Sometimes, I might take a sip and say to myself, "Eh. The Diet Coke's not so good today," as if I'd just sampled a cut of prime rib at Texas Roadhouse rather than sipped from a cup of carbonated water, aspartame, caramel coloring, and other stuff I have not memorized. That is to say, I've been training for this soda ranking for a very long time.

A good fast food Diet Coke, to me, has a vibrant, nose-tickling carbonation burn — not a mild, Pellegrino-like buzz. Its flavor notes are strong, not watered down, with balanced sweetness. The cup itself doesn't end up flavoring the beverage — we already know Diet Coke tastes different in cans versus bottles; containers matter! And if it accomplishes all this at a relatively cheap price, even better.  

I had hoped that whatever fast food Diet Coke filled this last-place position would land there merely for being the least delicious performer out of an octet of tasty sodas. Unfortunately, my local Zaxby's (a Southern fried chicken chain) picked the day of my taste-test to hand over one of the most out-of-tune beverages I have experienced in a very long time. My notes for this soda literally start, "Love the cup, hate the contents. I don't know what happened here, but this is disgusting." I didn't even take notes on the carbonation, so shockingly foul was the flavor. Even if it had been beautifully bubbly, it would have been something of a "lipstick on a pig" situation. 

The color of the soda was as expected, but it tasted like it was time for them to change out the soda syrup, and nobody had realized it yet. It was so weak (and oddly tinged with ... was that root beer?) that I felt like I was ranking all the La Croix flavors again. I don't know if ranking the swill I was handed is fair shakes to Zaxby's or not, but I'd already pulled out of the long line, as one tends to do when ordering from a drive-thru. In the end, these fast food restaurants had one shot to please my Diet Coke taste buds, so Zaxby's lost. That said, the cup was smooth Styrofoam and filled with divine pebble ice. Too bad the Diet Coke was ... whatever that was.

With Zaxby's Diet Coke being so much of an oops-tastic outlier, you might say Popeye's is technically last place. The contents of that little paper cup were, indeed, Diet Coke; they were just the least awesome in terms of carbonation, which made enough of a difference to send the drink to seventh place. Popeyes was Anthony Bourdain's favorite fast food fried chicken — no word on his views of its Diet Coke. As for myself, however, I've got a few words. 

For me, the saddest part is that Popeye's Diet Coke actually had a pretty good flavor, with a nice, concentrated sweetness. That poor carbonation made it an underwhelming experience, though — one that I paid $2.29 for. That's fairly standard for a fast food Diet Coke, but the best soda in this ranking was $1.99, a gap in value for money that could rankle a bit in this economy (seriously, why is fast food so expensive now?). However, it mustn't go unsaid that, although fast food joints have standard practices for consistency, they may sometimes have an off day when the soda fountain's internal workings aren't quite up to muster. (Looking back up at you, Zaxby's.)

In this battle of the fast food Diet Cokes, the King couldn't quite best Popeye the Sailor Man. On the first sip, I noted that this contender for the throne was pretty good, but it didn't have that super-pop of concentrated flavor I taste in superior fast-food Diet Cokes. However, it was a perfectly okay beverage, meaning it was the kind of Diet Coke you'd just want to drink with food rather than being worth a trip around the drive-thru to order by itself. Unlike Popeye's Diet Coke, the carbonation here was okay — not weak — but it lacked the delightful "angry water" punch I really look forward to when I sip cola through a straw.

After taking comparison sips of this one alongside two other outstanding contenders, I realized the Burger King soda almost had a stale flavor. If you're a typical consumer, though (not one taste-testing or working with a palate honed by years of experience), you might be unlikely to notice this.

Wendy's has always been one of my favorite fast food spots. I'm partial to it to the point where I knew I needed to force myself to be stringently unbiased when tasting its Diet Coke (I employed the same degree of Wendy's-specific objectivity when I tasted and ranked fast food salads worst to best). I was already smitten enough with Wendy's face beaming up from a clear cup that allowed me to see all the bubbles clinging to the inside. But as appearance wasn't a factor in this ranking, no show of twinkling pockets of gas would turn my head.

My push for objectivity revealed a remarkably middle-of-the-road beverage. It had better carbonation than Burger King's and a sweeter, slightly more concentrated flavor, but those features were barely a half-step in quality up from BK's cup of DC. To be clear, this was a tasty beverage, but one I'd order only with a tasty Wendy's burger. It's pretty, but nothing to write home about.

You can always count on Chick-fil-A having a long line. Maybe it's the food; maybe it's the fact that it has the best fast food customer service. The day I arrived for my taste-test, the chain's multiple drive-thru lines were at least a dozen cars long, making this the only spot I went inside to obtain my Diet Coke. The queues here were shorter but long enough for the attendant to reply to my order, in a friendly yet bemused way, "Really? That's it?" I didn't tell him that the Styrofoam cup of Diet Coke he handed to me was a contestant in this competition; I just let him think I love Chick-fil-A Diet Coke that much.

The thing is, that wound up not being the case. Don't get me wrong — it wasn't bad at all; it was better than Wendy's. In fact, it was comparable to the Number One soda on this list in terms of flavor quality and intensity. The carbonation hit okay, but not quite as buzzy as that of the first three contenders. If I had to categorize this one, it would be a Diet Coke that I'd mostly order to wash down food rather than make a special trip for. But if I ever found myself not hungry at a Chick-fil-A (a passenger along on a ride, for instance), I just may order one. I'd go with easy ice, though, as the chain fills its cups high with those little icy pebbles, making it a soda that's over relatively quickly.

Pebble ice and Styrofoam can go a long way in influencing one's perception of a fast-food soda. So can an outrageously minuscule price tag for a cup so big you can't even photograph it on your dashboard. At Sonic Drive-In, the attendant merrily informed me that my order for a small soda would actually cost me more than if I upgraded to a large. On Sunday mornings, you see, Sonic Drive-In (at least mine, at least right now) does happy hour. So, that hulking behemoth you see in my perilously stretched hand up there cost me only $1.27.

Inside that cup was a Diet Coke with a satisfying, nose-burning carbonation level and a sweet, balanced flavor. It was a lovely sensory experience, the kind of drink you tote around with you all day without its flavor withering away through dilution faster than is fair. It wasn't the winner, though, merely because two more bested it — and one of them didn't even have a fancy cup.

I'm as surprised as you might be at the placement of Arby's Diet Coke in this ranking. I've got nothing against Arby's; I just never, ever eat there, and I nearly forgot its existence until research revealed that this roast beef sandwich chain is a purveyor of Coca-Cola products (it just seems "Pepsi" to me). As I popped the straw into the lid and prepared to sip, I expected something akin in quality to Burger King's Diet Coke, which came in a similar paper cup.

But folks, this Diet Coke was really, really good. The carbonation was extremely nice, bubbling in the mouth and burning down the throat in just the right way. The flavor was vibrant and sweet, almost a dead-ringer for the first-place soda except for the paper cup and the price: it was $2.59. On a regular day, Sonic's would have cost $2.79 for that large size, and the Number One soda happened to be one of the cheapest. Nonetheless, good game, Arby's; good game.

Here it is in all its bubbly glory at the coveted first-place spot in this ranking. This is what it's all about: that crispy, happy burn the moment you swallow your first sip, and an engulfing, Arctic-cold wave of unique Diet Coke flavor that you just don't get at any of the other fast food spots. This is the soda I crave — and it's not just me. McDonald's Diet Coke has something of a fan club online. Generally speaking, people think it's the GOAT, and anecdotes abound in attempts to explain its almost uncanny superiority: A special recipe? A strategic ice ratio?

The McDonald's website actually has an FAQ dedicated to the question, "Why does Coca-Cola taste so good at McDonald's?" Let's extend the response to the diet version as well. As it turns out, there is no special recipe, but the syrup ratios are tweaked to account for melting ice diluting the flavor. Before being run through the fountain, the water is filtered with a top-tier system and also chilled (which helps preserve carbonation), as are the syrups. Speaking of which, instead of syrups delivered in clear plastic bags, they arrive at Mickey D's in stainless steel tanks that insulate them from destructive elements like heat and light. All in all, the Golden Arches know what's up when it comes to serving sodas that make the internet buzz.

My assessment of each Diet Coke included both taste and carbonation level. An ideal flavor was balanced and strong, with no "cup" flavor in the drink, and the perfect carbonation was robust, offering that iconic "angry water" burn both on the palate and in the throat. To experience the drinks at their best and most undiluted, I tested each soda in the car as soon as it was handed to me. I continued to sip throughout the next half hour, often comparing one drink to the next. Price was not a factor (most of the drinks hover around the same price), but if a really, really good one was notably cheaper than the others, this could help break a tie.