GT3 & GT4 Classes Rebuilt

July 29, 2026

New for Update 2.1 is a major handling overhaul for the GT3 and GT4 classes.

These classes have been completely transformed, bringing an array of changes and improvements. In this blog we’ll break down what's changed, and why this is a significant moment in the evolution of Project Motor Racing.

GT racing is the sweet spot of modern motorsport. You get variety. You get manufacturers people recognise. You get different engine layouts, different characteristics, different strengths, different weaknesses, and just enough Balance of Performance to keep everyone close enough to start an argument by Turn 1.

So for Update 2.1 the GT3 and GT4 classes have received a complete handling and physics overhaul, overseen by Aris Vasilakos and his team.

Nothing has been left untouched with these cars. But before we go into the details, here’s the headline news.

GT3: Sharper, More Sensitive, More Alive

The GT3 class has received a major update. The changes focus on balance, braking, traction behaviour, aero platform sensitivity, and the overall feel of the car across a stint. GT3 cars now respond more clearly to ride height, pitch, load transfer, and driver input, especially when braking hard, attacking kerbs, or trying to lean on the aero at speed.

Aerodynamics have also taken a significant step forward, including more realistic rear aero map behaviour and increased pitch sensitivity. In other words: what the car is doing on its suspension matters a lot more now.

GT4: Rebuilt from the Wheels Up

The GT4 class is meant to be approachable, but never simple. These are race cars with real weight, real movement, real braking demands, and a driving style that rewards commitment without giving you endless grip as a participation trophy.

For Update 2.1, the GT4 class has been systematically remodelled. Suspension geometries have been reworked, dampers and bumpstops have been revised, and chassis behaviour has been brought closer to what you expect from a proper modern GT4 car: progressive, physical, readable, and rewarding when driven cleanly.

The result is a class that brings the different platforms to life. Cars feel more connected under braking, more communicative through the apex, and more honest when you ask too much from the tyres.

Okay, so now back to what you came here for...

The Tyres Know What You Did Last Lap

The GT3 and GT4 tyre simulation has been fully reworked, with new attention given to load sensitivity, deformation, adhesion, and heat behaviour.

Tyre surface flash heat is now much more sensitive. Push too aggressively, slide too much, or carry excessive slip angles, and your tyres will show the result in both performance and longevity.

If you throw the car around chasing one lap, surface temperatures can spike and cost you performance. If you abuse the tyres lap after lap with too much slip angle, you will get excessive wear. If you keep asking the front axle to do three jobs at once, it will eventually stop taking your calls.

But drive smoothly, keep the car balanced, and bring the tyre into the window properly, and you will find more performance.

And that means you now get to manage your stint your way: push and pit early, or take a more conservative approach and go longer.

Cold Tyres Need Respect

One important warning before everyone discovers it the hard way: cold tyres are tricky. Warm them up before activating hero mode.

Do not leave the pits, point the car at Turn 1, and assume the grip has arrived early out of politeness. It has not.

Cold tyres are now less forgiving, more nervous, and easier to overdrive. A big spin on cold tyres will also hurt your tyre wear instantly. And warming them by abusing them will not work, because that does not work in real life either.

Build temperature properly. Brake progressively. Avoid big slides on the out lap. Put load into the tyres cleanly and let them come alive before you start chasing qualifying heroics.

The grip is there. You just have to earn it first.

The Wheels-Up Rebuild Details

The rebuild of GT3 and GT4 starts where all proper race-car behaviour starts: with the platform.

Suspension geometries have been reworked. Dampers have been revised. Bumpstops have been rebuilt and reimplemented with a much bigger role in how the cars behave, especially under aerodynamic load.

That matters because in modern GT racing, the car is not just sitting on springs and hoping for the best. Ride height, pitch, platform control, bumpstop engagement, aero balance, and mechanical grip are all having a very loud conversation with each other.

The aim is to make the cars feel more connected across braking, corner entry, kerb strikes, mid-corner load, and corner exit.

Drivetrains, Mass, and Balance

Update 2.1 brings adjusted, data-derived gear ratios and final drive ratios across the two classes.

Inertia has also been modified. Centre of gravity values have been adjusted. Ballast has been updated. The goal is a more authentic relationship between weight, rotation, stability, throttle application, and the way each car changes direction.

Engines have also been rebuilt, with enhanced turbocharger implementation, updated engine inertias, and more refined throttle response.

That means the individual cars in both classes will feel different because the mass, power delivery, engine response, and drivetrain behaviour are all working together to give each model its own rhythm.

Some cars will ask for patience. Some will let you lean harder. Some will punish greedy throttle like they have been waiting all lap for the opportunity. The result is a field where the cars feel meaningfully different.

Find the one that suits your style.

Aero Has Had a Major Rewrite

Aerodynamics have been through a very significant rewrite. This includes a more realistic implementation of aero maps, resulting in much greater pitch sensitivity, especially for the GT3 cars.

Dive under braking and the aero platform changes. Attack a kerb and the platform changes. Carry too much pitch, too much load transfer, or too much drama, and the aero balance will have a few notes for your consideration.

This is especially important in GT3, where aerodynamic performance is a major part of how the car generates speed and stability. The car is no longer just “grippy because GT3”. It is more sensitive to how you place it, how you support it, and how cleanly you keep the platform working.

Drive it properly and it will come to you. Treat it like a rental kart with a rear wing and it you will be scratching your head at your lack of pace.

Brakes, Heat, and Ducts Matter More

Brake behaviour has also been updated, including brake disc temperatures, brake heat transfer into tyres, and the effect of brake ducts.

Brake ducts now influence both brake temperature and aerodynamic drag, meaning setup choices carry clearer trade-offs. Open them too much and you may pay for it in drag. Close them too much and you may pay for it in brake temperature. Ignore the whole thing and, well, the car will find a way to explain why this matters.

Usually at the end of a straight.

Heat management now matters across the full system: brakes, tyres, surface temperature, and stint consistency. That makes driving style and setup choices more important, especially in longer sessions.

Smooth Is Fast. Again.

The goal of this overhaul is simple: make GT3 and GT4 feel more alive, more readable, and more rewarding.

These classes should encourage proper racecraft. Brake with control. Rotate the car cleanly. Avoid leaning on slip as a substitute for technique. Bring the tyres up to temperature. Manage the platform. Attack when the car is ready, not when your ego says the onboard camera is rolling.

GT racing is popular because it sits right on that line between accessibility and depth. The cars are recognisable, the racing is close, and the margins are small enough that one bad input can turn a good lap into an educational moment.

With the GT3 rebuild and GT4 refinements, that experience now sits deeper in Project Motor Racing.

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