Section 2: Equipment
2.1 Car Eligibility and Body
All cars competing in the NASCAR Cup Series must conform to the specifications set forth in the NASCAR Rule Book and the applicable NASCAR-approved templates. The current approved manufacturers for the Cup Series are Chevrolet (Camaro ZL1), Ford (Mustang Dark Horse), and Toyota (Camry XSE). Car bodies must conform to the manufacturer-specific NASCAR-approved body templates. Any body panel, aerodynamic surface, or component not explicitly approved in the Rule Book or by a NASCAR Technical Bulletin is prohibited.
Cars must display the correct manufacturer hood logo, rear decklid logo, and quarter-panel logo consistent with their declared manufacturer. The car number must be displayed on both door panels, the roof, and the rear bumper in a font and size conforming to NASCAR specifications.
2.2 Chassis and Structure
The Next Gen car uses a common steel space-frame chassis supplied by NASCAR-approved manufacturers. The chassis must be constructed per the dimensional specifications in the NASCAR Rule Book. Significant structural components — including the roll cage, door bars, roof halo, and fuel cell containment structure — must conform to NASCAR-approved specifications and may not be altered beyond permitted adjustments. The roll cage must be constructed of minimum 1.75-inch diameter, 0.090-inch wall thickness chromoly or 4130 steel tubing in the primary hoop, per the specifications chart in the Rule Book.
2.3 Engine Specifications
NASCAR Cup Series cars use a naturally aspirated, pushrod V8 engine with a maximum displacement of 358 cubic inches (5.87 liters). The engine must conform to the specifications in the NASCAR Engine Rules, including:
- Cylinder block: Must be an approved NASCAR Cup Series spec block. The cylinder bore centers and deck height must conform to approved specifications.
- Compression ratio: Maximum 12.0:1 as measured per NASCAR procedures.
- Carburetor/Fuel delivery: Holley four-barrel carburetor (on most oval tracks); electronic fuel injection (EFI) is approved for select events.
- Restrictor plates / Tapered spacers: At Daytona International Speedway and Talladega Superspeedway, cars must run NASCAR-supplied tapered spacers to limit horsepower to approximately 510 hp. On intermediate and short tracks, engines produce approximately 670–750 hp.
- Rev limiter: A NASCAR-supplied engine control module (ECM) is mandatory. The ECM enforces pit road speed limits and functions as a rev limiter.
2.4 Weight Requirements
The minimum weight for a NASCAR Cup Series car, including the driver but without fuel, is 3,400 pounds (1,542 kg). Cars found below minimum weight following an event may be subject to disqualification. Weight may be added to the car in the form of ballast, which must be securely mounted and located per Rule Book specifications. Ballast may not be located in the driver's compartment in a manner that creates a safety hazard.
2.5 Suspension
The Next Gen car uses a double-wishbone front suspension and an independent rear suspension (IRS) — a significant change from the previous solid rear axle configuration. Suspension geometry adjustments (camber, toe, caster) are permitted within defined ranges. Spring rates, shock absorber settings, and sway bar configurations are adjustable within the parameters defined by NASCAR.
2.6 Transmission
A NASCAR-supplied five-speed sequential (H-pattern sequential) gearbox is mandatory in the Cup Series. Gear ratios are selectable from NASCAR-approved combinations specific to each track. Automatic transmissions are not permitted.
2.7 Fuel
The official fuel of the NASCAR Cup Series is Sunoco Green E15, an unleaded fuel containing 15% ethanol, supplied exclusively by Sunoco as the official fuel supplier. No other fuel may be used. The fuel cell (safety fuel tank) has a maximum capacity of 18 gallons (68.1 liters). The fuel cell must be an approved, commercially available bladder-type unit conforming to SFI Specification 28.1 or FT3/FT3.5 equivalent, enclosed in a steel container mounted in the approved location behind the rear axle.
2.8 Tires
Goodyear Eagle tires are the exclusive tire supplier for the NASCAR Cup Series. Tire compounds are selected by Goodyear and NASCAR specific to each track and event. Teams may not alter tire compounds, add traction compounds, or modify tires in any way. Tire pressure must be set within the ranges specified by NASCAR for each event. Teams receive a defined allocation of tires per event as published in the event entry information. Used tires must be returned to Goodyear following the event.
2.9 Wheels
The Next Gen car uses an 18-inch aluminum center-lock wheel (single-lug nut, 10-lug pattern on the hub) supplied by NASCAR-approved manufacturers. Wheel diameter is standardized at 18 inches. The center-lock design replaced the five-lug wheel used on previous-generation cars, affecting pit stop procedures significantly.