TLDR: iRacing 2021 Season 4 Release Notes

This is a truncated version of the release notes, focusing on major changes that affect the various road racing championship series here at Xtreme Motorsports.


We would ask that all members try out the GT4 changes and provide feedback to the league so we can determine how best to move forward with the Sportscar Series, our longest standing championship.


All Cars


Pit Stop

Fuel leaks are now always fully repaired during pit stops - no exceptions. They are also fully repaired before refueling begins.


Damage Modeling

The “No Damage” mode has been updated for improved interaction with collisions.

- - This damage mode now allows the simulation to execute full vehicle damage, allowing the physics to perform accurately for more realistic collisions. Then, after the crash has settled and a very short duration, all vehicle damage is immediately repaired. This alleviates impossible physics behaviors that could occur under the previous system which utilized some indestructible and non-pliable objects. These changes should make vehicle collisions more realistic and predictable, even when racing with damage disabled.

- - This system operates when using either the original damage model or the New Damage Model.


A new system message is now displayed when the Simulator is using any damage model other than normal damage.


Fixed a long-standing bug where player wheels would sometimes pass through opponent cars and/or their wheels.

- - This fix should significantly improve the consistency for car-to-car interactions for all cars.


New Damage Model

Fixed an issue where wheel damage forces were sometimes getting applied in the incorrect direction and angle.


Dallara P217

Some parameters have been adjusted for the repair of the engine, wheels, and body panels.


Global Mazda MX-5 Cup

iRacing setups have been updated.


All GT3 Cars

- - Tires have been updated for the GT3 class. You can expect different limit feel and degradation behavior. Grip will be slightly lower on cold tires, peak after a few laps, and then drop noticeably before holding steady until the tires are heavily worn.

- - Temperature sensitivity and wear are now enabled on the clutch for this vehicle.

- - Minimum cold tire pressures have been increased to 21.5 psi (148 kPa) to bring operating hot pressures closer to real life.

- - ABS control has been adjusted slightly. Proportional gain has been increased. More aggressive pressure cuts now allow the system to converge on target slips more quickly.

- - Imperial toe adjustment values in the garage are now displayed as 0.000 in.

- - Fixed an issue where the rear wing angle range was incorrect.

- - iRacing setups have been updated.

- - Animated driver and pedals have been updated.


Audi R8 LMS

- - Vehicle minimum weight has been reduced by 5 kg

- - Aerodynamic downforce has been increased slightly.


BMW M4 GT3

- - New engine and backfire sounds have been added.

- - Fixed an issue where vehicle damage was incorrectly increasing downforce.

- - Fixed an issue with the tooltip information for the rear wing angle adjustment range.

- - iRacing UI renders of this vehicle have been updated.


Mercedes-AMG GT3

- - Front roll center height has been increased.

- - Rear bump steer has been reduced.

- - Aerodynamic balance has been shifted forward slightly.

- - Fixed an issue where the traction control positions were reversed.


Porsche 911 R GT3

- - Torque has been reduced slightly.

- - Aerodynamic drag and downforce have been increased slightly.

- - Vehicle minimum weight has been increased by 2.50 kg.

- - Front-end geometry has been updated to reduce pitching through braking zones.

- - Fixed an issue where vehicle damage was incorrectly increasing downforce.


All GT4 Cars

- - Tire construction parameters have been updated.

- - Aerodynamic model data and mapping have been updated.

- - iRacing setups have been updated.


BMW M4 GT4

- - Pitch limits have been updated.


Porsche 718 Cayman GT4 Clubsport MR

- - Vehicle minimum weight has been increased by 2.50 kg.


There are other small graphical updates to cars and tracks which may be of interest: the full notes may be found here.