Every year, the Coca-Cola 600 at Charlotte Motor Speedway somehow finds a new way to exhaust everyone involved. And that is exactly what makes it one of NASCAR’s toughest races. There is, of course, the 600 miles aspect, but the way the race keeps piling challenge after challenge onto drivers and teams as the night progresses is what few people understand.

Now, the former Hendrick Motorsports crew chief, who called races for Jeff Gordon and Dale Earnhardt Jr. across some of their most successful seasons, has offered a candid breakdown of what makes Charlotte so uniquely punishing, particularly for the Next Gen car, even as the same model remains one of the best aerodynamic fits for the speedway.

NASCAR insider explains Charlotte’s challenges

“Well, first of all, this car is really built for these high-speed intermediate tracks: the mile-and-a-half and the two miles. But Charlotte, remember, is a little smaller than Michigan; it’s about the same size as Kansas, but it has a little more grip.”

Charlotte’s surface and the width of the track mostly allow close racing. And considering how aero-sensitive the Next Gen cars are, it becomes difficult to keep up the pace in dirty air.  This, paired with the rough asphalt, makes the cars difficult to handle on multiple parts of the track.

Ross Chastain had famously noted last year: “When you run the top of the track up by the wall, it’s almost like a washboard – if you’ve driven on a dirt road that’s rough and it’s really bouncing really aggressively – that’s what Turn 1 up by the wall feels like.”

Another unique thing about the Coca-Cola 600 is the sheer endurance that drivers require. The 400 laps run around Charlotte in close to five hours (For example, the 2019 race lasted 4 hours and 50 minutes) require immense mental strength and reliability from the car. While these goals are still easier to achieve, there is one other issue that hampers the race for many.

“As tires age, the better cars still are going to advance, and it’s gonna help the cars when the grip goes up. The other big magic of this racetrack, I think, is the changing conditions,” Letarte added.

The race begins at 6:00 PM ET. Then, after roughly 150 miles in, typically as Stage 2 gets underway, daylight departs for darkness to take over, the track lights come on, and Charlotte transforms. As one of the most sensitive tracks when it comes to weather changes, Charlotte often catches teams by surprise, making them react to a different race altogether.

Crew chief Brian Wilson spoke before the race last year: “That’s the first question we have to ask is, how are the conditions going to be different than what we just practiced in? You want to make sure your balance is strong there, but we know the track could change. This is one of the most temperature-sensitive tracks. We know that going into the night, it can change. It’s a long race.”

But the most apparent struggle only begins in the later stages, as not speed, but the real mind games begin.

“When you look at the race itself, and you break it down, you’ve got to make a pit stop in every stage. So it takes a minimum of seven pit stops to get through the race. And it’s so easy to get locked into this mindset that you gotta pit in the middle of every stage and at the end of every stage,” Letarte said, hinting at the same.

The Coca-Cola 600 is the only race on the NASCAR Cup schedule to feature four stages, which can force pit crews into predictable cycles. But the teams that win here tend to be the ones willing to break that rhythm at the right moment. Moreover, Charlotte’s length also means that dominance early means very little.

William Byron was leading most of the race last year and seemed headed for a victory until Ross Chastain, adjusting throughout the race and making use of his opportunities during the 600-mile run, crossed the finish line ahead of him. This is one of those rare races where a team, despite starting in the middle of the pack, actually has the potential to work its way up towards victory.

Hence, it is clear why this weekend is paired with the Indianapolis 500 as NASCAR and IndyCar’s informal “Double Challenge.” Only Tony Stewart, in 2001, completed all 1,100 miles of both races in one day.

Letarte did say that there is a “magical marriage between the Next Gen car and Charlotte Motor Speedway,” which is a real thing since the car’s aero characteristics suit the long backstretch, and its construction was designed with tracks like this in mind.

But that compatibility doesn’t make Charlotte simple. If anything, it adds a cost to everything. Which is precisely why the crew chief’s voice in the pit box matters a lot.