iRacing’s 2026 Season 4 Release Will Bring 4 Cars and 3 Rebuilt Tracks on Sept. 15

The PC racing sim will also test multiclass pace cars, add multi-threaded physics and new interface tools, and expand AI racing to 8 cars and 19 track configurations.

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Two Caterham race cars drive through a circuit during an iRacing race.

iRacing will begin its 2026 Season 4 on Sept. 15 at 12:00 a.m. UTC, bringing 4 new cars, 3 rebuilt tracks, physics upgrades, and a wide range of simulation and interface changes. iRacing announced version 2026.09.09.01 in its Steam announcement as one of the sim’s 4 major annual releases.

The new car lineup includes the Aston Martin Valkyrie AMR-LMH, Caterham Academy, Caterham 420R, and Gen 4 Grand National. Road America, Mid-Ohio Sports Car Course, and The Milwaukee Mile have each been rescanned and rebuilt, with the new versions fully replacing their older counterparts.

Summit Point Raceway and Road Atlanta will also receive major artwork updates. The release will further lay the groundwork for multiclass starts with dedicated pace cars for each class. That system must first pass a final shakedown in Week 13’s iTested series before it can officially join the IMSA iRacing Series.

Under the hood, iRacing’s physics processing engine will support multi-threading, which the developer says will make object interactions more accurate. Car Rule Sets will expand to 81 vehicles, while the Global Mazda MX-5 Cup and Sprint Car will receive major vehicle mechanics overhauls designed to bring their handling closer to their real-world counterparts.

UTF8 support will cover chat messages, display names, and iRacing files such as Replays, Setups, and Camera set filenames. The new Reference Car UI will show live control inputs from a reference car during solo sessions, giving drivers another way to study technique.

Two new interface widgets are also arriving. Pit Summary will provide controls and information for pit stops, while Car Damage will display general vehicle health for the Global Mazda MX-5 Cup, Toyota GR86, BMW M2 Racing (G87), Renault Clio R.S. V, Ray FF1600, Mini Stock, and Lucas Oil Off Road Pro 2 Truck. The F9 Black Box is being reworked into a Quick Access panel, and a new Minimal UI mode will let drivers strip the interface down to essentials while keeping selected elements pinned.

The Fuel Calculator Widget will use more data for its stint estimates, and the Track Map Widget will receive usability improvements. iRacing’s launcher will also get a rebuilt Team Registration process, refreshed Leagues area, and individual pages for Past Results. Solo sessions launched from an Official Session will be able to carry that event’s BoP into Test Drive sessions for more relevant practice.

AI racing will expand to 8 additional cars, including the Aston Martin Valkyrie AMR-LMH, both Caterhams, Gen 4 Grand National, Chevrolet Corvette C7 Daytona Prototype, Formula Renault 2.0, [Legacy] BMW Z4 GT3, and [Legacy] Riley MkXX Daytona Prototype – 2008. AI support will also reach 19 new track configurations, while rain racing will be available for the Valkyrie, both Caterhams, and all non-Oval configurations among the new tracks.

The iRacing Companion App was rebuilt recently to support future development, and the release also includes hundreds of vehicle setups. The 2026 Season 4 features page provides more information about the new content and systems.

Patch Notes for iRacing 2026 Season 4

The biggest changes cover new cars and tracks, multi-threaded physics, interface tools, launcher systems, multiclass race starts, rain support, and expanded AI racing. The full 2026 Season 4 release notes contain the detailed breakdown.

Aston Martin Valkyrie AMR-LMH
Caterham – Academy and 420R
Gen 4 Grand National
Road America (Updated Laserscan & Fully Rebuilt)
Mid-Ohio Sports Car Course (Updated Laserscan & Fully Rebuilt)
The Milwaukee Mile (Updated Laserscan & Fully Rebuilt)
Summit Point Raceway (Major Art Update)
Road Atlanta (Major Art Update)
Multiple Pace Cars Multiclass Starts available in select official series, beginning with the IMSA iRacing Series
Multi-threaded Physics Processing
Full UTF8 character support
New SIM UI Widget: Pit Summary
New SIM UI Widget: Car Damage (Global Mazda MX-5 Cup, Toyota GR86, BMW M2 Racing (G87), Renault Clio R.S. V, Ray FF1600, Mini Stock, and Lucas Oil Off Road Pro 2 Truck)
New Sim UI Black Box: F9 Quick Access
Sim UI Update: Minimal/Pinned UI Mode
Sim UI Update: Fuel Calculator Widget improvement
Sim UI Update: Track Map updates
Global Mazda MX-5 Cup (significant vehicle update)
Sprint Car (significant vehicle update)
Car Rule Sets are now supported on 81 vehicles
iRacing Launcher Feature: Team Registration Refactor
iRacing Launcher Feature: Bring Official Session BoP into Test Drive
Rain racing for THREE more vehicles! (Aston Martin Valkyrie AMR-LMH, Caterham – Academy and 420R)
AI Racing is now available with EIGHT new cars: Aston Martin Valkyrie AMR-LMH, Caterham – Academy and 420R, Gen 4 Grand National, Chevrolet Corvette C7 Daytona Prototype, Formula Renault 2.0, [Legacy] BMW Z4 GT3, and [Legacy] Riley MkXX Daytona Prototype – 2008
AI Racing is available at NINETEEN new tracks: Auto Club Speedway – Competition, Interior, and Moto, Federated Auto Parts Raceway at I-55, Kansas Speedway – Infield Road Course and Road Course, Mid-Ohio Sports Car Course – All configs, Oswego Speedway – Dirt, Road America – All configs, The Milwaukee Mile – All configs, and USA International Speedway – Dirt
Hundreds of the highest quality vehicle setups

Which part of iRacing’s 2026 Season 4 release are you most interested in? Share your thoughts in the comments, and follow us on X, Bluesky, YouTube, Instagram, Steam, and Telegram.

From NASCAR, rallycross, and Aussie Supercars to sports cars and Grand Prix racing, iRacing has it all. All you need is a computer, a gaming wheel or game pad that simply plugs into the USB port of your computer and an Internet connection. iRacing centrally organizes all of the racing for you with over 150 cars and tracks, 40 official series , or you can choose to host your own race or race in one of over 800 private leagues.