NASCAR Alejandro Alvarez | NASCAR Digital Media

NASCAR debuted a new version of its Next Gen prototype this week at Auto Club Speedway in California, with William Byron behind the wheel. This version of the car is dubbed the “P3” as it is the third version built, the first one being used for aerodynamic testing and the second being tested by a variety of drivers over the past few months. We spoke with NASCAR representatives and some sources familiar with the project to find out how the car is progressing.

The biggest change with the P3 Next Gen variant is that the car has transitioned from its traditional five-lug wheels to a new single-lug variant. This is a large departure for NASCAR but is common in other forms of motorsports, such as GT sports cars and Australian Supercars. BBS has been announced as the sole vendor of the new wheel, and the prototype was wearing a BBS RE series wheel, which is common in other racing series as well as on street cars like the Porsche 911.

According to a source we spoke to, NASCAR is considering a lease program for the wheels but has not made a final decision on the project at this time. NASCAR confirmed that new suspension uprights were built in order to support the new single-lug hubs, and a source told us that the car is employing aluminum uprights.

While single-lug wheels are not common on street cars, the 18-inch size can be found on all three street variant of the cars that race in the Cup series. That could very well help bring the looks of the Cup cars closer to the street cars. It also offers an opportunity for the manufacturers to offer similar-looking, racing-inspired wheels.

Other notable changes to the car include a redesigned front clip which can be seen in the photo posted here by NASCAR EVP Steve O’Donnell on Twitter. In the photo we can see that the upper frame rail under the hood is a bit taller now, with an angle added towards the front bumper. A NASCAR representative confirmed that these changes were made after feedback from the teams regarding access to engine. Per our source, the previous version of the front clip did not allow removal of the valve covers with the engine in the car. That would have been an issue come race day, as teams often remove the covers during race weekends to change valve springs.

The pictures from the test released by NASCAR show that subtle changes were made to the body with the removal of rear exhaust heat extractor that has allowed the exhaust pipe to be moved closer to the rear wheel as well as the removal of vents that were previously present in the rear bumper. We can also see a small piece of the new rear upright peeking out behind and below the rear wheel in one of the photos. The front of the car is mostly the same, but lower inlets that were taped at the previous test have now been completely removed.

The cage structure in the car appears to be freshly built—this version of the cage has not been painted yet. The tubing looks to be as thick if not thicker than the previous version, and an extra bar has been added toward the front right behind the A-pillar. The rest of the cabin appears to be similar to the previous car, but according to one of our sources it has been lengthened in order to accommodate taller drivers. Many fans are likely curious if the Ryan Newman crash at Daytona had any impact on the changes to this car but the build of the “P3” was already likely in progress and any data gained from that crash is unlikely to have made an impact on this version of the Next Gen prototype.

According to another source, additional changes have been made underneath the car. Updates include modifications so that driveshaft removal would be easier, along with fixes at the corners for the suspension links and sway bars. Those sway bars have been relocated due to changes to the structure, and the improvements will make them easier to access for changes at the track.

NASCAR’s test for this P3 car was ended earlier than expected due to a crash that happened around 6 or 7 laps into a 25-lap run. Byron, the test driver, detailed what happened: “That time, I just got loose and figured I’d be able to save it but wasn’t able to. It just came all the way around. I had a number of similar moments in the race Sunday and was able to drive out of it. That’s what caught me off guard the most. It’s part of testing though, learning where the line is with what the car can do.”

He followed up by noting changes in the behavior of the car: “It was tough to get a hold of at first, just how fast everything is,” Byron said. “The tire doesn’t have the same sidewall, so there is not the same amount of slip that you can hang the car out. You just have to get used to that timing and rhythm of when the car does step out, how quickly can you catch it when it slides the front tires, how quickly does it come back. All those things are a lot different from what we do now.”

All of the drivers that have tested the car have commented on how much extra effort this Next Gen car takes to drive, and Byron’s comments were met with some degree of enthusiasm that it could bring better racing, but some the car’s behavior may be related to its current stage of development. NASCAR appears to be taking feedback from the drivers and making changes to make the car more stable in certain aspects.

One such aspect is the steering. which is a new rack-and-pinion system that is different from the recirculating-ball system in use on the current generation of Cup cars. Our sources state that feedback from early tests indicated that the steering was “twitchy.” NASCAR has made adjustments to try to stabilize it. Offsets appear to have slightly changed for the wheels, based on the photos released and according to a source. The goal there was to make scrub radius adjustments in order to provide less sensitive steering.

Although the steering concerns are apparently going to be addressed, it is still possible that, based on the aerodynamic configuration of the new car, drivers will still have to adjust to increased effort. One of the new aero components on this car is the rear diffuser, which was likely added to combat dirty air from the car. (Even that has seen changes since the last test, as it is now tucked more underneath the rear bumper. This should alleviate some of the concerns about the position of that diffuser and how it might impact bumping and drafting in races.) The first true tests of how the cars behave, including multi-car tests, will take place over the next few months.

With P3, it sounds like NASCAR is nearing the final steps of completing its production race car. Company Senior Vice President of Innovation and Racing Development John Probst states that they “feel like this car is probably 99 percent what we’re going to compete with next year, and then some of the vendors that we’ve selected have been able to make parts available that will be identical to what we’re racing next year.” Probst also confirmed that changes made to the car were related to feedback from mechanics. “It’s a mix of things that make it easier to work on, which is probably one of the biggest criticisms of the first car is that it was difficult to work on, so we implemented a bunch of changes from a mechanic’s standpoint to make it easier.”

NASCAR declined to confirm any vendors other than BBS for the wheels, but based on the comments above by Probst, it sounds like that many are locked in already. Job listings for welders at a new facility in Concord near the NASCAR R&D Center, along with a business registration, appears to show that Technique, Inc has been chosen as the chassis supplier. Technique currently supply kits for teams to build the current version of the car, so it is not surprising that it would be chosen to build the Dallara-designed chassis.

In addition to that, a source familiar with the negotiations states that NASCAR is likely to select Öhlins as the supplier for the spec shock for the racing series. Öhlins was recently acquired by Tenneco, which has been involved in NASCAR for decades through some of its other brands such as Moog and Federal-Mogul. Tenneco also owns the Monroe brand, so Monroe could supply the shocks if it receives the contract directly.

The P3 car is expected to test again after the Atlanta race that is coming up this weekend, and we’ll be following along and delving into some deeper analysis to find out what final tweaks are in the cards before the Next Gen car is ready for action.