Do iRacing, ACC and Le Mans Ultimate judge incidents differently?
This is the last part of Fault lines. We've looked at how often reviewers agree, which moves get posted and what makes agreement drop. The obvious remaining question is whether the sim you race changes any of it.
Blame rates differ by sim
The share of verdicts that blame the poster, for the seven sims with enough threads:
Share of verdicts that blame the poster, with 95% ranges. Each sim has 183 to 446 threads with enough verdicts.
| Sim | Cleared | Shared | Blamed |
|---|---|---|---|
| iRacing | 50% | 27% | 23% |
| GT | 53% | 22% | 25% |
| Le Mans Ultimate | 49% | 25% | 27% |
| Assetto Corsa | 43% | 30% | 27% |
| Forza | 46% | 25% | 29% |
| ACC | 45% | 25% | 30% |
| F1 | 42% | 27% | 31% |
iRacing posters are the least likely to be blamed. After adjusting for year and thread size, F1 threads run 9.6 points higher on blame than iRacing, ACC 6.9 points higher, and Assetto Corsa, Le Mans Ultimate and Forza about 5 points higher. Gran Turismo isn't clearly different.
There is a caution worth stating plainly. These sims are different communities in different years: Le Mans Ultimate threads only exist from 2025, and the F1 flair probably gathers a different audience from the others. When we compare only 2025 and 2026, when all the sims overlap, just two gaps remain statistically detectable against iRacing: ACC (+7.6 points) and Le Mans Ultimate (+4.9, only just). The F1 gap is the weakest of the headline numbers.
Agreement is similar almost everywhere
Agreement, measured by Krippendorff's alpha, sits between 0.18 and 0.26 in every sim. Gran Turismo is the highest (0.26), ACC next (0.25), and iRacing, Forza, F1 and Assetto Corsa all land at 0.23 to 0.24. Le Mans Ultimate is the lowest, at 0.18, and in 2025 and 2026 its pairs of reviewers agree about 5 points less often than on iRacing. That's the one agreement difference we'd call a lead rather than noise, and we ran several comparisons, so we'd want more data before leaning on it.
The simple conclusion: whichever sim you race, expect reviewers to agree about half the time.
What each sim's threads are about
What people argue about does differ.
Share of threads naming each move, by sim.
- Intent and retaliation appears in 30% of iRacing threads, 27% of Le Mans Ultimate and 26% of Gran Turismo threads, but only 10% of F1 threads.
- Multiclass traffic is 16% of Le Mans Ultimate threads, 8% of iRacing, 5% of ACC and Assetto Corsa, 2% of Gran Turismo and under 1% of F1.
- Spins and loss of control are a bigger part of Le Mans Ultimate threads (13%) than of most others (6% to 10%).
- Netcode comes up most on iRacing (6%).
- Defending, rejoining and dive-bombs are about the same everywhere.
What we can't say
The data can't tell us why. The difference in blame could come from the sim, from who plays it, from what kind of races people post, from the era, or from how strict each sim's own penalty system is, which sets what people think is normal. We would be guessing, so we won't.
What it does show is that a verdict in one community is not a universal one. A driver whose reviewers come from a different background will be judged against a different baseline.
What to take from the series
Across four posts the picture is consistent:
- Reviewers agree about half the time, in every sim.
- Most disputes are about space, and next most about intent.
- The words "alongside" and the quality of the clip hurt agreement most.
- The sim you race changes how often you're blamed, and mostly not how well people agree.
For a league, the lesson is to stop treating community opinion as the standard. Use your own ruleset, define the words that matter, set an evidence standard, and measure yourself: take ten past incidents, have two stewards decide independently, and see how often they match.
A small note about us
Sim Racing Steward is sim-agnostic and works from the ruleset you supply, so your league's definitions apply whatever you race. Run those ten past incidents through it and compare its fact report and draft decision with what your stewards did. Sign up now; free accounts include 15 credits a month.
Data: 6,563 first-person threads from r/Simracingstewards, sampled per sim (iRacing 1,000; Le Mans Ultimate 1,000; ACC 900; Gran Turismo 900; F1 700; Assetto Corsa 700; Forza 509). Verdicts are detected automatically and are not perfect. Sim comparisons use thread-level resampling for confidence ranges.