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The top two divisions in NASCAR are the NASCAR Cup Series and the NASCAR Xfinity Series. However, both Ford [Mustang] and Chevrolet [Camaro] enter the same car body names in both series, so, are the cars actually different? Indeed, these two cars are very different, but, it wasn’t always that way. We dive into the key differences between a NASCAR Xfinity Series car and a NASCAR Cup Series car.
Throughout the early to mid-2000s, the NASCAR Cup Series and Xfinity Series essentially ran the same type of car, but, the Xfinity Series car was usually fitted with less horsepower. That changed in 2007 when the Cup Series unveiled the new “Car of Tomorrow”, which had an emphasis on safety and parity. That’s where the dissension began.
The Xfinity Series Car
The Xfinity Series still used the old “Gen 4” cars until 2010 at Daytona, when the Xfinity Series version of a “Car of Tomorrow” was introduced. It had all of the benefits of a Cup Series “Car of Tomorrow”, including a larger cockpit, insulating foam in the doors, and a new front splitter. The car did not have as much horsepower as the Cup Series car, however.
Aside from some minor tweaks here and there, the Xfinity Series car has remained relatively unchanged. There was the introduction of composite bodies in 2017, but, it’s still largely the same formula as it was in 2010. Think COT-era Cup Series car.
The Cup Series Car
The Next-Gen car, introduced in 2022, was all about cost savings and parity. Whereas many parts and pieces of the older cars were designed and fabricated by the teams and manufacturers, NASCAR largely made the new cars “Spec” cars.
It’s also a completely different design philosophy than past cars. The addition of things like rear diffusers and sequential shifters means the car is more closely related to a sports car than a traditional stock car.
Xfinity Series engines put out less horsepower than Cup Series cars do, but, it’s not as drastic as some might think. While the Cup Series puts out 670 horsepower, the Xfinity Series cars pull 650 according to FloRacing.
This was much more drastic in past years when the Cup Series was putting out over 900 horsepower in the 2010s. For a brief time between 2019 and 2021, the Xfinity Series actually put out more horsepower on bigger tracks because the Cup Series implemented a 550 horsepower package. There has been some flexibility with this over the years.
The Cup Series cars have a 5-speed sequential shifter installed. Xfinity Series cars, on the other hand, have the traditional H-Pattern 4-speed shifter. The Cup Series had an H-Pattern shifter until the Next-Gen era.
This comes from two different design eras in NASCAR. As we mentioned previously, the Xfinity Series car is based on the formula from the early 2010s, where a sequential shifter was never even thought of. The result of the extra speed in the Cup Series gearbox is that shifting is far more common on short ovals than in the Xfinity Series.
The Cup Series cars use wide tires with a single lug nut on the car. The Xfinity Series cars, on the other hand, use the traditional tires with 5 lug nuts. Again, the Xfinity Series car is based on the older NASCAR car formula.
The result is that Cup Series cars tend to have more grip in the corners via the wider tires. However, Xfinity Series crews have a small hazard with the 5-lug nuts. If NASCAR sees a lug nut is loose on an Xfinity Series car, the team is penalized.
The Cup Series underbody is fit with a rear diffuser that helps to create downforce. The Xfinity Series cars are not equipped with this, and they just have a traditional undercarriage.
The rear diffuser creates more downforce for the Cup Series cars, which creates more grip, particularly on road courses and short tracks. That is not there for Xfinity Series cars, which means the cars do not drive quite as well on those tracks.
The Xfinity Series and Cup Series could not be more different from each other. They both come from different times and different design philosophies in NASCAR history, and the result is two very different race cars and racing series.
