iRacing has detailed its Season 4 2026 update, confirming a substantial package of new cars, rebuilt circuits, physics improvements, UI features and further progress on Career Mode and the next-generation graphics engine. The August development update also confirms the arrival of the Aston Martin Valkyrie AMR-LMH, two Caterham models, major revisions to several existing cars and a new multiclass race start system. New Cars and Rebuilt Circuits The headline car addition is the Aston Martin Valkyrie AMR-LMH, developed using telemetry, chassis data and direct engineering input to reproduce the characteristics of the V12-powered prototype. iRacing says the project required extensive work to accurately model the car’s mechanical behavior, aerodynamics and chassis dynamics before it was considered ready for release. iRacing is also adding the Caterham Academy and Caterham 420R as a single purchase. The Academy is aimed at novice racers and will initially compete in Class D series, while the more powerful 420R will be positioned in Class C. Both cars bring a lightweight, highly mechanical driving experience that sits between traditional sports cars and open-wheel machinery. Three existing circuits have been completely rebuilt using new laser scans captured in 2026. Road America, Mid-Ohio Sports Car Course and the Milwaukee Mile will replace their older versions while remaining available at no additional cost to existing owners. The older versions of those tracks will be retired once the new scans are released with Season 4. Road America also receives new East and West configurations using the Turn 5 bypass, while Milwaukee gains a new road course layout. In addition, Summit Point Raceway has been rebuilt with new models, textures, vegetation, curbs and surfaces, while Road Atlanta receives updated track textures, 3D curbs, foliage and scenery ahead of Petit Le Mans. Major Car and Physics Updates The Mazda MX-5 receives one of