iRacing’s Season 4 2025 patch notes have been released, revealing three new cars, a new track and a host of improved features coming to the sim.
iRacing’s Season 4 2025 changelog has revealed several new features coming to the sim later today (9th September 2025), as well as previewing an entirely new user interface.
Three new cars, one new track, an overhauled hybrid system and several circuit overhauls are the main features of the new build, which also includes VR improvements and the facelifted BMW M4 GT3 Evo.
Check out all the details and the full changelog below.
iRacing’s GT3 and GT4 ranks have been boosted by the appearance of the Aston Martin Vantage EVO GT3 and Ford Mustang GT4.
iRacing states that the Vantage’s inclusion is part of a wider deal to bring more Aston Martins to the sim, perhaps indicating that the likes of the Valkyrie Hypercar could make it to iRacing in future.
The Indy NXT Dallara IL-15 will also be unlocked today, which may be linked to iRacing Studios’ recent official IndyCar video game announcement. The IndyCar-supporting NXT series will be added to the game when it releases for PC, PlayStation 5 and Xbox Series X|S in 2026.
As an added bonus, the facelifted BMW M4 GT3 Evo will appear in-game too, replete with new taillights, headlights and aerodynamics. The Evo replaces the standard model going forward.
The Autódromo Hermanos Rodríguez makes its debut in iRacing today, bringing the venue for the Mexican Grand Prix to the sim.
The circuit also hosts a round of the NASCAR Cup Series, which uses a different layout. In fact, seven different configurations will be available to race in iRacing, including a flat, one-mile oval.
The UK’s Oulton Park has been given a significant overhaul, with textures, shaders and foliage given a complete revamp.
However, don’t expect any 2025 revisions, as the track will still look fundamentally as it did when it was originally scanned nearly 15 years ago.
World Wide Technology Raceway, Sonoma, Charlotte Motor Speedway and North Wilkesboro Speedway have been completely rescanned and updated to modern standards, while Chicago Street Course, Circuit of the Americas, Daytona International Speedway, Texas Motor Speedway and Watkins Glen International have been given a modern-day spruce up.
The Gen4 NASCAR has been updated with AI racing functionality, with the same car featuring revised draft mechanics for more believable wheel-to-wheel racing.
In one of the most important changes to the Season 4 2025 build, iRacing has reworked how its hybrid model works.
The power output of the GTP cars is now blended between the internal combustion engine (ICE) and motor generator unit (MGU), which reflects how Le Mans Ultimate handles its Hypercar hybrid system.
By default, GTP cars are locked to a 50% state of charge target and a balanced deployment strategy.
The Ferrari 499P LMH car also works similarly, but its MGU will only deploy its battery after 190 kph and to a maximum of 100 kW. iRacing has decided not to implement the Virtual Energy concept in this build, and has hinted that it may not happen in future either.
The 499P will receive future updates to its MGU, however, allowing players to adjust the amount of power produced by the MGU at high speeds.
The Mercedes-AMG W12 and W13 and LMP1 cars will behave similarly to before, just with refined regeneration and brake blending functions. iRacing plans to add IndyCar’s hybrid system to the Dallara IR-18 in the Season 1 2026 build, with the LMP1 hybrids set for an overhaul, too.
The Ford Mustang GT4 will be arriving in tomorrow's 2025 Season 4 update! 🔥 pic.twitter.com/tMKDO33JHc
The GT4 class has been given a total physics and tyre overhaul, much like the GT3 cars were revamped back in iRacing’s previous build.
The class has been balanced as per the real-world IMSA Pilot Challenge ruleset, so tyre warmer temperatures have been reduced and power outputs have been adjusted, loading to more realistic minimum corner and top speeds.
This should lead to slower lap times overall, with higher top speeds offset by lower grip levels all-round. ABS, traction control, dampers and aero settings have all been revised too, including adjustments to the class’s wet tyre performance.
iRacing’s new UI is here, implementing modern technology to improve the sim’s functionality.
This includes revisions to the Black Boxes, the merging of replay and normal graphics settings, and a more efficient camera tool for virtual photographers to become familiar with. Generally, widgets are easier to manipulate, with the full list of updates shown in the changelog at the bottom of this article.
Dynamic foveated rendering has been added to iRacing, helping headset users obtain more efficient game performance without detracting from visual fidelity.
The system lowers the quality of the graphics outside of the user’s predicted area of focus dynamically, improving frame rates. Players will need an RTX2000 GPU series or better to make use of the feature.
For several other changes in iRacing’s Season 4 2025, check out the changelog below.
A handful of updates have been made to the Official iRacing Sporting Code, including:
Track debris is now mentioned for Yellow Flags.
Information surrounding the Connection Black Flag has been added
Additional visitor vehicles have been added.
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