Ask anyone what the biggest problem with the Next-Gen Car is, and many will say the same thing: dirty air. If it is such a big problem in the Next-Gen era, what causes the car to be so bad in traffic? Today, we dive into what exactly causes the issues with the Next-Gen car in traffic.
Perhaps the simplest reason why Next-Gen cars tend to struggle in traffic is due to just how close they are together on speed. It doesn’t take a rocket scientist to figure out that if cars run at the same speed, it will be very difficult to pass. A car has to go faster than another to make a pass.
This is most apparent on superspeedways, where the cars run in big packs, but the draft does allow cars to manipulate the air and make passes in the right circumstances. It’s the worst on short tracks, where the cars are so even that they cannot separate themselves from each other, forcing them to all just fall in line and play “Follow the Leader.” The below graphic from Auto Racing Analytics highlights this.
Dale Earnhardt Jr. highlighted this as an issue on road courses as well. He discussed this along with the concept of no stage cautions after the 2023 Sonoma race, which he called “Dull.”
Denny Hamlin also made the same point in an “Actions Detrimental” episode this season. He said, referring specifically to speed and lap time, “You’ve got to have haves and have not if you want actual passing.”
However, this is most prevalent on short tracks and road courses where aerodynamics is not as big of an issue. On the bigger tracks, we can start digging into the aerodynamic issues of the Next-Gen car.
As mentioned earlier in the article, the Next-Gen struggles with “Dirty air.” Denny Hamlin discussed this in a recent “Actions Detrimental” episode comparing the Cup Series Next-Gen car to the NASCAR Xfinity Series car.
First, Hamlin blames NASCAR for the struggles in dirty air, saying NASCAR didn’t realize the car struggled in traffic until just before the debut. He called the Next-Gen cars the “Worst” in traffic.
Later, when discussing the Xfinity Series car, he talked about why those cars can put on the racing that they do. In that series, the trailing cars can manipulate the air on the rear of the car in front of them, making that car not handle as well. The Cup Series cars do not have that ability, which gives the leading car a massive advantage, particularly on high-speed tracks.
This was quite prevalent in the most recent race in Indianapolis, where the cars struggled to follow and pass each other in “Dirty Air”. It was also evident during the finish of the Cup Series race at Dover, where Hamlin won by aero-blocking Kyle Larson in the closing laps.
We know the problem, but what is the “Why”? Hamlin specifically hones in on the aerodynamic design of the Next-Gen car, fit with an underwing complete with a rear diffuser.
Rather than cars using over-body aerodynamics to create downforce and increase grip, the underwing does much of that work. That air cannot be as easily manipulated by the trailing car, meaning that the leading car has a significant advantage. The trailing car can somewhat alleviate this by switching their line on multi-groove tracks, but not every track has multiple grooves.
When combined with the other factors of the Next-Gen car that create similar speeds, it only makes it harder to deal with turbulent air. If a car is not fast enough, then overall speed cannot overcome the issue of “Dirty air.”
Why does the Next-Gen struggle in traffic? It somewhat depends on the track type, but it is mainly down to the design of the Next-Gen car itself. Is there a fix?
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