Race Sim Studio’s GT-M series has become the closest thing Assetto Corsa has to a modern GT3 standard, and the GT-M Bayer i6 Evo is a perfect example of why. It’s built around the BMW M4 GT3 EVO, the updated GT3 package BMW introduced for the 2025 season, and it arrives as part of RSS’s GT-M Championship Phase 2 lineup.
This is also one of those mods where the quality is immediately obvious. Visually it’s sharp, feature-complete, and polished in the way RSS cars usually are. The bigger story is how it drives. The Bayer i6 Evo isn’t difficult because it’s snappy or unpredictable. It’s difficult because the braking and rotation behavior pushes drivers to rethink what normally works in a modern GT3.
Find the Bayer i6 on the Race Sim Studio store:
The BMW M4 GT3 EVO is BMW M Motorsport’s refinement of its GT3 platform, designed to improve consistency and drivability over a race stint. BMW has described the EVO’s updates as focused on areas like optimized aerodynamics, improved chassis components to reduce tire wear, and updated lighting and bodywork details.
Power figures in GT3 are always regulation-dependent, but BMW’s own consumer-facing materials commonly reference the M4 GT3’s straight-six turbo output up to 590 hp, with the important caveat that output can vary with regulations. The key takeaway is not the exact number, it’s the character: a turbocharged inline-six GT3 platform that’s meant to deliver stable, usable pace.
That usable pace theme shows up clearly in the RSS version, even if the handling balance still demands respect.
These are broad real-world context notes that help frame the experience:
The Bayer i6 Evo follows the same RSS workflow as the other Phase 2 cars.
Version 1.1 is worth mentioning because it targets CSP compatibility. RSS notes that the update aims to resolve conflicts and display issues with newer CSP builds and adds auto rain light control.
This is classic RSS.
Exterior: proportions, aero surfaces, lighting, and small details are excellent. The car looks official in replays, and it holds up even when the camera is close.
Interior: cockpit fidelity is equally strong, with clean materials, readable displays, and the kind of detail density that makes the cabin feel modern and purpose-built.
Textures and reflections are consistent across the car, and nothing stood out as visually broken during testing.
The sound is very close to what Assetto Corsa can realistically deliver. It’s detailed, credible, and suited to the car’s character, but it’s not the kind of sound that grabs attention on its own.
That’s not necessarily an RSS issue. The real M4 GT3 is not universally loved for its engine note compared to the most dramatic GT3 cars, and Assetto Corsa’s sound engine still has limits compared to newer sims. The result is a sound package that feels 99% there, just not goosebump level.
RSS includes the level of systems detail expected from their GT-M line:
Liveries are also a highlight. There are 10 included, and aside from the standard carbon option, the variety is strong, ranging from stylized designs to copyright-safe takes on real-world inspirations.
This is the section that defines the Bayer i6 Evo. It’s fast, but the fast lap does not come from brute force.
The biggest challenge is the braking phase and how the car behaves when trying to combine braking with rotation.
That combination forces an adjustment. The car does not reward the typical approach where you commit and lean on the fronts the same way some GT3s do. Finding the correct entry technique takes time, and it’s one of the few GT3 mods that genuinely makes drivers feel like they need to rewire habits.
Once the car is settled, mid-corner balance feels like a standard RSS GT3. Slightly understeery but not lazy, and generally stable.
On exit, it can be a little more playful than some GT3s, but it’s still within what feels believable. It’s not a car that constantly snaps. It’s a car that wants clean throttle application, especially because the stock TC intervention is lighter than expected. Compared to the RSS McLaren GT3 Evo-style entry, the Bayer requires more personal throttle discipline.
Kerb behavior is slightly better than many GT3 mods, but nothing unusual. Tire behavior is stable and predictable with no weird grip spikes.
Force feedback is excellent. It’s detailed, confidence-building, and communicates load changes clearly, which helps massively with the tricky braking character.
The Bayer i6 Evo was tested under the standardized OC Racing benchmark:
Best valid lap: 1:34.538
The lap time suggests there’s potentially more pace available, but extracting it consistently is limited by that entry balance. When the braking phase clicks, the car feels properly fast.
* Unrestricted / outside GT3 regulations
There are three small negatives worth noting:
None of these are dealbreakers, but they shape the experience.
Within the Assetto Corsa mod market, the Bayer i6 Evo sits in a premium tier. RSS’s GT-M ecosystem remains one of the most consistent modern GT experiences available for AC, and Phase 2’s pack structure reinforces that.
The most obvious comparison point is that other teams have also produced M4 GT3 content, including URD, which makes for an interesting future head-to-head. But in terms of polish, systems depth, and complete package feel, RSS sets a high bar.
Value is straightforward here.
At £4.19 standalone, the Bayer i6 Evo is priced like a low-risk pickup, and the overall quality is easily worth it. It also slots into the Phase 2 pack model cleanly for anyone building the full grid.
The RSS GT-M Bayer i6 Evo is a great car with a difficult character. It looks incredible, feels premium, and delivers excellent feedback, but it also demands adaptation in the braking phase that many GT3 mods simply do not require.
For drivers who want a GT3 that feels fast without feeling automated, this is one of the best additions to RSS’s GT-M lineup, and the Assen benchmark time shows it’s already a serious contender in the early leaderboard.
What car mod should be reviewed next?
Drop suggestions in the comments, and include the class so it can be added to the Lap Time Challenge leaderboard.
OC Racing Lap Time Challenge at Assen: The Benchmark We’re Using for Every Assetto Corsa Mod Review - OC Racing says:
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