The rules package of the 2019 season served as the starting point of the Next Gen's development. The prototype, built by Richard Childress Racing using a generic body, was tested for the first time on October 8 and 9 by driver Austin Dillon at Richmond Raceway. The second test of the car was done at Phoenix Raceway on December 9and 10 with Joey Loganobehind the wheel of it. Erik Jones drove the car in its third test, which was held at Homestead–Miami Speedway on January 15 and 16. The fourth test was at Auto Club Speedway with William Byron on March 2–3. John Probst, NASCAR's senior vice president of racing innovation, commented that the "P3" prototype Byron tested was nearly 100 percent of the final product. Due to the COVID-19 pandemic, all racing was postponed through the month of May. Further testing that was scheduled to take place at Atlanta Motor Speedway with Clint Bowyer on March 16 and 17 was still on since the Next Gen car testing was exempted from NASCAR's indefinite ban on all testing. However, this decision was quickly reversed after the health crisis got worse. A handful of manufacturers, teams, and drivers alike indicated their hope for the debut of the car to be postponed one year to 2022 as a result of the lost testing time. On March 30, 2020, it was reported that NASCAR was taking a serious look at pushing back the rollout of the new car to 2022. NASCAR officially confirmed these reports on April 2, 2020, and the car's debut was pushed back a year to allow for enough testing time after the postponement of all events through May.
Design
Aero and downforce packages
The Next Gen car is expected to use a stepped front splitter, aerodynamic vents on the hood and a redesigned side skirt, all of which are designed to reduce the amount of sideforce in the cars. A notable addition to the Next Gen car is the rear diffuser, which is set to be used in NASCAR for the first time. NASCAR have conducted various tests on the wind tunnel to have the car to generate more downforce using the rear diffuser. Adjustable aerodynamic components are also expected to be used to accommodate the various track types in the schedule.
Technological improvements
Spec chassis
In contrast to the body-on-frame construction of previous generations, the Next Gen car will use a carbon fiber tub. This construction allows the driver to be positioned farther from the door panel of the car, further increasing its safety. Dallara was initially rumored to be the exclusive supplier of the new chassis, but it was revealed that Technique recently opened a shop in Concord, North Carolina, indicating that they will manufacture the chassis for NASCAR teams.
On March 2, 2020, NASCAR announced that the traditional 15-inch steel wheel with the five-lug pattern will be replaced by a new 18-inch aluminum wheel that uses single center-locking lug nut. The wheels will be manufactured by German firm BBS.
Refueling system
The Next Gen car is expected to use a clamp-on refueling hose similar to those used in IMSA. This would eliminate the use of the traditional gas cylinder canister carried over the pit wall.
