2026 Spring Darlington Setup Notes

The 2026 spring Darlington setup notes detail the largest set of change since the Next Gen car was introduced there. Let’s examine what’s different and what impact it might have on the racing.

Forty Percent Less Downforce

The Gen-7 makes the majority of its downforce underneath the car. That feature allows manufacturers to really lean into brand-specific body styling because body details don’t impact aerodynamics as much. Previously, when the car body was primarily responsible for generating downforce, small changes created a headache for NASCAR as they tried to ensure that all the car were equivalent rather than equal.

The diffuser generates downforce by controlling the way air travels under the car. The photo below shows the diffuser outlined in yellow. A non-short-track car has a diffuser skirt with five strakes. The strakes organize the air coming out from under the car the same way grocery store lines organize checking out.

The short-track package doesn’t include the five strakes. That makes the air less organized, which means it doesn’t exit as quickly. That, in turn, decreases how much downforce the car generates.

A typical rear downforce is around 1000 lbs with all five strakes in place. With the strakes removed, we’re now talking around 600 lbs — 40% less downforce. That’s a meaningful reduction.

Speed depends on grip. Grip depends on downforce. Less downforce means less grip and more of a challenge to driver the car. Here’s one of the most important rules of racing: You can only go as fast as your slowest tire.

You can only go as fast as your slowest tire

Dr. Diandra

The downforce decrease is primarily in the rear, so drivers are not only dealing with less downforce, they’re also dealing with a very differently-balanced car.

More Horsepower

This year, 80 more horsepower power the rear wheels. Instead of the old 670 hp package, drivers will have 750 hp. How much of a difference is this?

• 80 hp is about 60,000 W (60 kW)
• A naturally-aspirated gas engine of about 1.2L produces around 80 hp. It’s like adding a 2024 Mitsubishi Mirage to the Cup Series car used here last year.
• A backup generator for a school or industrial site would be around 80 hp.

For reference, a typical midsize sedan would have 170-200 hp.

Softer Tires

The tire setup at Darlington will feel familiar: it’s the same tires they used last weekend at Las Vegas. The left-side tire (D-5284) was used here last year, the but right-side tire (D-5290) is new to Darlington. It’s first appearance was at Kansas Speedway last fall.

This is the latest step in a ongoing experiment by NASCAR and Goodyear to make tires meaningful. If a tire shows no changes in performance, there’s no motivation for crew chiefs to bring their drivers in hope better tires compensate for the time penalty for a pit stop.

The garage has been a lot more careful this year in their comments about the tire. They’ve realized that blaming tires for crashes is a large part of why Goodyear was reticent to make softer tires. The media has also gotten onboard, with commentators making a point to note that crew chiefs frequently go well below Goodyear’s recommended inflation pressures. If tires blow, it’s usually the team’s responsibility.

Higher Temperatures

The average high temperature in Darlington at this time of year is 63°F to 71°F. Predicted temperature Sunday at race time is in the mid 80s. Conditions will be more like a fall Darlington race than a Spring one.

A hotter track means less grip. Less grip means more of a challenge for the drivers to go fast while still retaining control.

So What Does It All Mean for the Race?

Teams ran the higher horsepower engine at Phoenix, so they have experience with that.

They’ve been using the strake-less diffuser at short tracks for some time.

Not only do teams have data on both tires independently, they also have data on the two tires used together from last week at Las Vegas.

Teams have lots of data from Darlington, in all types of weather conditions.

But this will be the first time they encounter this specific combination of factors — and NASCAR didn’t given them an extended practice as they often do with larger-than-normal rules changes.

Here are the main impacts:

• Softer tires wear faster.
• More horsepower offers more opportunities to accelerate out of corners, spin the tires, etc. — which also wears the tires more.
• Faster and greater tire wear leads to faster and greater changes in the car’s balance.
• As Christopher Bell noted during his media availability Saturday, the chances of a driver spinning out on his own are greater.
• Darlington is a mentally taxing track. Mistakes will be easier to make and thus likely be more costly.

Unfortunately, most of our chances to talk with drivers were before practice, so we don’t have much information from them about how differently the cars handled with the new rules package.

My Take

There have been a couple of a times, most notably at Bristol, where everyone has really hyped up the possibility of a really exciting race. That doesn’t always happen.

Drivers were predicting a ‘crash fest’ and ‘chaos’ well before they got on the track with the new package and I got a feeling listening to some of them that they’re playing it up just a bit.

The one thing that I do believe is that drivers are having a whole lot more fun with this rules package. Some drivers believe they can drive a difficult car better than other drivers, which will give them an advantage. Some of the lower-level drivers expressed that they expect to benefit from chaos, as happens at superspeedway races. Every driver who doesn’t finish the race moves them up a position and gains them another point.

Unless, of course, they’re the ones not finishing.

That’s your 2025 spring Darlington setup notes.