Bug report: Comprehensive Physics & Track Bug Report: Inverted Elevation/Load Calculations & Sardegna Road Track A Mesh Seam

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PrinceISR

PrinceISR

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Israel
Israel
I am writing to submit a comprehensive technical bug report detailing fundamental physics calculation errors and a track geometry issue in Gran Turismo 7:

1. Core Physics Bug: Inverted Elevation Gradient and Load Calculation
Through rigorous testing (such as constant full-throttle testing in lower gears across inclines versus declines), it has become evident that the physics engine's elevation gradient logic is fundamentally inverted.
  • The engine and chassis physics consistently behave as though an upward slope is being calculated as a downward slope, and vice versa, regardless of RPM range.
  • This core calculation error misallocates vehicle mass load and powertrain resistance, distorting net torque, momentum, and vehicle behavior across all tracks and vehicle classes.

2. Powertrain Impact & High-Level Shift Meta
Because of this inverted gradient logic, powertrain behavior near peak RPM is skewed:
  • On Inclines: The vehicle experiences artificial torque allowance, forcing top-tier drivers to adapt to an unnatural short-shifting meta.
  • On Declines: Powertrain drag behaves incorrectly, subduing expected gravitational acceleration.
Adjusting the foundational gradient-to-load scaling parameters is critical to restoring true physical realism.

3. Sardegna - Road Track - Layout A (Turn 7 Surface Mesh Seam)
Approaching Turn 7 on Sardegna - Road Track - Layout A (on the downhill section following the sweeping left curve), there is a distinct geometry seam in the track's collision mesh. Transitioning across this point causes an abrupt vertical drop/clip into the surface, resulting in violent suspension compression, force feedback spikes, and momentary grip loss.

Please investigate the core elevation gradient logic in the physics engine and patch the surface collision seam at Turn 7 on Sardegna Road Track A in an upcoming update.

Best regards,
PrinceISR
 
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I don't think your testing is very vigorous because I've had cars almost come to a stop because of severe inclines, for example the long uphill section at the Nordschleife. Or maybe it was downhill all along :confused:
 
i didint knew that this community is so toxic. my english is not that great and in my words there is something wrong with going uphill and downhill. when u go downhill the rev limiter should hit faster since the weight of the car is pushing the engine and uphill the rev limiter should hit slower since te engine is pulling the car and struggle producing momentum. it feels like the dev messed something up and no one noticing that since u have no knowledge about physics. i regret using this forum tbh i knew its bad idea
 
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PrinceISR
i didint knew that this community is so toxic.
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That isn't what the word "toxic" means. "Toxic" is when negative behaviour from an individual spreads unchecked to poison an entire userbase/community; a community itself cannot be "toxic", only poisoned by toxicity.

And, for reference, not immediately agreeing with you (having presented nothing) is not a "toxic" behaviour, even though a lot of people used to being agreed with unconditionally like to use it that way.
PrinceISR
my english is not that great and in my words there is something wrong with going uphill and downhill.
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And that's what a video of this issue would, in part, overcome without need to get an LLM to generate your thoughts for you.

Create a video. Show the issue you are perceiving. Bear in mind that there are several fuel economy missions that rely on uphill being uphill and downhill being downhill, and that they wouldn't work at all if these were transposed.


Also, we cannot do this:
PrinceISR
Please investigate the core elevation gradient logic in the physics engine and patch the surface collision seam at Turn 7 on Sardegna Road Track A in an upcoming update.
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... because we're not Polyphony Digital. We're an independent media site with no role in the development of or support for Gran Turismo or any other game.
 
Famine
That isn't what the word "toxic" means. "Toxic" is when negative behaviour from an individual spreads unchecked to poison an entire userbase/community; a community itself cannot be "toxic", only poisoned by toxicity.

And, for reference, not immediately agreeing with you (having presented nothing) is not a "toxic" behaviour, even though a lot of people used to being agreed with unconditionally like to use it that way.

And that's what a video of this issue would, in part, overcome without need to get an LLM to generate your thoughts for you.

Create a video. Show the issue you are perceiving. Bear in mind that there are several fuel economy missions that rely on uphill being uphill and downhill being downhill, and that they wouldn't work at all if these were transposed.


Also, we cannot do this:

... because we're not Polyphony Digital. We're an independent media site with no role in the development of or support for Gran Turismo or any other game.
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thank u for your serious response i respect that.

now back to the subject, idk if its affecting fuel or engine momentum, but as what i feel its a bug that needs to be fixed and ill explain again and u can check it yourself if u play this game, and ill provide a video.

so ill say again, when u go uphill the rev limiter hits faster/reaches to its limit - faster then going downhill which in real life is the complete opposite of that.

i know that people here are not polyphony digital devs (of what i know) but i hope this bug would reach them if the players would care about this bug and maybe they will fix it because it doesn't make sense to me and i hope it doesn't affect the competition of this game.

here are 2 videos with 2 different cars i tested it at the nurburgring nordschleife:

mini cooper:


ferrari:


thank u.
 
So your issue is actually with the rev limit behavior...? Why not just say that instead of all the AI babble? Yes the way the rev limiter works is a bit weird and always has been, but it's not a significant issue.
 
If you hide the rev limiter and mute the sound, do you feel that the cars behave incorrectly on inclines/declines?

The way the limiter behaves in those videos does seem strange, but in my experience, the cars actually behave as you would expect when driving up or downhill; i.e., you often need to drop gears in order to get up steep hills, some cars are incapable of getting up the steepest of hills, etc. I cannot see any evidence of a bigger problem, can you?
 
I'm not sure I see any issue in those videos. You're applying full throttle in first gear and it appears as though you're bouncing off the rev limiter faster going downhill than uphill...what's the issue?

...actually it's sort of difficult to tell visually how much either direction in the video is actually downhill or uphill. What happens on a more pronounced incline? Also what happens if you aren't bouncing off the rev limiter? Like if you switch to 2nd gear in those vids are you able to accelerate faster uphill than down? Because that I would agree would be odd (and I haven't really ever felt like that was the case in the game myself).
 
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PrinceISR
so ill say again, when u go uphill the rev limiter hits faster/reaches to its limit - faster then going downhill which in real life is the complete opposite of that.
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When you go uphill the car slows down faster each time the rev limiter cuts in, that’s why it’s bouncing faster, because the engine can start to produce power again more quickly.

When you go downhill, it takes more time to slow down the car so it takes more time until the revs drop to the point where the engine can produce power again.
 
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