WRC Cars (Group Rally1)

WRC Cars (Group Rally1)

Definition and Historical Significance
Group Rally1 represents the premier technical regulations established by the Fédération Internationale de l'Automobile (FIA) for the World Rally Championship (WRC), officially superseding the previous World Rally Car formula in the 2022 season. The introduction of Rally1 marked one of the most radical technical overhauls in rallying history, debuting hybrid powertrains in top-tier rallying and ushering the WRC into the electrified era. Restricted strictly to factory manufacturer entries, only three marques—Toyota, Hyundai, and M-Sport Ford—were homologated to compete between 2022 and 2024.

Chassis Architecture
The most significant technical departure in Rally1 lies in its chassis construction. Unlike the previous World Rally Car era, which mandated a production-based bodyshell, Rally1 machinery is built around a bespoke 100% tubular spaceframe chassis engineered in-house by each team, with bodywork only required to visually resemble the respective road-going model. This architecture affords teams substantial structural freedom while dramatically enhancing occupant safety. The spaceframe integrates a built-in safety cell with a T45 high-strength steel roll cage, offering crash protection far beyond that of any production monocoque.

Powertrain
The Rally1 powertrain combines an internal combustion engine with a standardized hybrid unit. The combustion unit carries over the 1.6-litre turbocharged inline-four engine from the World Rally Car era, fitted with a 36 mm air restrictor to generate approximately 380 hp. The spec hybrid system, developed by Compact Dynamics, features a 3.9 kWh lithium-ion battery and a Motor Generator Unit (MGU) delivering an additional 100 kW (approx. 134 hp) and 180 Nm of torque under boost, lifting total system output to over 500 hp. The hybrid battery is recharged via regenerative braking and plug-in capability within the service park. All Rally1 cars run entirely on 100% fossil-free sustainable fuel, marking a historic first for the WRC.

Transmission and Suspension
Rally1 cars utilise a permanent all-wheel-drive system with front and rear mechanical limited-slip differentials; however, the active centre differential from the World Rally Car era has been eliminated in favour of a spool-type mechanical centre differential with a fixed torque split. The transmission has also been simplified from a six-speed to a five-speed sequential manual gearbox, with steering wheel-mounted paddle shifters replaced by a traditional floor-mounted mechanical shift lever. Suspension travel has been scaled back substantially from 380 mm to roughly 250–270 mm, and liquid-cooled brakes have been outlawed. These cost-containment measures were introduced to rein in engineering complexity and operational budgets.

Aerodynamics
Aerodynamic packaging on Rally1 cars is noticeably toned down compared to the previous generation. Front wings, side skirts, rear spoilers, and underbody channels face tighter technical restrictions; rear diffusers have been completely outlawed alongside concealed brake and cooling ducts. Furthermore, the extensive use of carbon-fibre aero components has been curtailed to minimize gravel impact damage and replacement expenses. This philosophy reflects the FIA's core objective: preserving high-speed visual drama while pivoting the technical arms race from aerodynamic downforce towards mechanical grip and powertrain reliability.

Phasing Out the Hybrid System
The Rally1 hybrid era spanned merely three seasons. In February 2024, the FIA Rally Commission confirmed the removal of the hybrid unit from Rally1 cars starting from the 2025 season. This decision was primarily driven by cost constraints, as the specialized hybrid systems proved exceptionally expensive to service and maintain—where heavy crash damage could run into hundreds of thousands of euros, placing an unsustainable financial strain on manufacturer teams. With the hybrid gear removed, minimum vehicle weight is reduced from 1,260 kg to 1,180 kg, the air restrictor is trimmed from 36 mm to 35 mm, and total engine output drops from over 500 hp to around 370 hp.

WRC27 Regulations Outlook
Ahead of the 2027 season, the top tier will transition to the next-generation WRC27 technical framework. Key regulatory shifts include: a standardized safety cell to drive down build costs; standardized dimensions for overall length, width, and wheelbase; further aerodynamic simplifications, including a complete ban on carbon-fibre aero surfaces; a return to production-derived 1.6-litre turbocharged engine blocks targeting around 290 hp; and drivetrains aligned closely with Rally2 specifications. A strict cost cap of RM345,000 (pre-tax) per car will be enforced, a sharp decline from the current Rally1 cost ceiling of nearly RM1,000,000. The updated regulations also permit independent vehicle tuners to homologate as "manufacturers", designed to draw new marques and privateer entries back into top-flight rallying.