I logged into GoG after a few days away to see what was happening, and there was an update for I'76. Curious to see what was happening, I hopped into a deathmatch against the bots in The Crater (Dover Lightning - Grand Sport).

Things that seemed to work:

1) Car physics.
2) AI.

Things that still don't seem to work:

3) Flamethrowers.

How much of #1 and #2 is new or not, or what the actual changes were, I'm not sure; so...

...tl;dr I made a thread for discussing the latest patch, since:

1) I can't seem to find any details.
2) I want to discuss the latest patch. ;)

(optionally, this might not be a new patch, and I've just somehow been missing it for an arbitrary length of time)

I wouldn't say "perfectly", since flamethrowers still don't work; and I haven't done a T.R.I.P. test, but yeah... Really cool. Dunno what they did, but overall, it seems to have worked - thanks for the conformation! :)

This update indeed seems to have made the game playable out of the box, but now the music doesn't work.

...I completely missed that.

Yeah, music is gone in my install, too.

Edit:

After further testing, the following arguments had the following results:

"i76.exe -d3d": 3/3 tests failed to desktop without reaching the opening text.
"i76.exe -glide": 3/3 tests launched to melee without any visible errors. Voodoo graphics, or voodoo-style graphics, were visibly present; car AI and physics appeared to work; flamethrowers did not work; music was not audible. Overall, aside from emulated voodoo graphics, it seems to play exactly the same as software mode.

Edit2:

The app "Lossless Scaling" has no visible effect on I76's scaling.
Turning Radeon Chill on or off (limited to 30 FPS or native 60 FPS) makes the game run at "normal speed" (30 FPS) or faster (60 FPS); however, AI and physics work as far as I can tell on either setting, in both software and Glide mode, albeit at accelerated rates.
I was able to successfully turn off VSync for software mode; an FPS between 240 and 440 did not cause any visible AI or physics problems. I was unable to successfully turn off VSync for Glide mode; it seems to have a VSync unrelated to "regular" VSync, as neither using Radeon settings nor environment variables from the page listed below had an effect.
GPU-based integer scaling seems to work properly with i76, in both software and Glide mode.

I found a number of settings for Voodoo-based graphics on this page - I cannot guarantee this page, nor anything found on this page:
https://www.oocities.org/tronik1/windows/games/games01.html

Further checking - a little T.R.I.P.:

1a) Route following experienced problems; either the AI or the physics - my guess is the AI, as the physics works elsewhere and does not appear to actually break here - results in Taurus jittering back and forth as his wheels, engine, and brake all engage or turn about once or twice per second; even with Glide running at 30 FPS.
1b) He did manage to drive on the road effectively, albeit someone bizarrely, at the speed limit; the real challenge would be the first race you do against him.
1c) It is possible that road following, not just route following, is broken; however, I have not had any real observation of AI cars on the road other than Taurus.

2) I was unable to get software mode limited to 30 FPS again.

3) 200+ FPS may break the AI in other ways, as an AI car in melee appeared to do a few tight circles before turning to fight me fairly effectively.

4) One or more of the environment variables listed on the above linked page, namely "SWAP_EN_WAIT_ON_VSYNC", "VSYNC", or "FX_GLIDE_SWAPINTERVAL", appear in fact to have an effect in Glide mode in regards to turning on or off the Glide FPS limit. I am uncertain if they are also the reason that software mode can no longer be limited to 30 FPS; how they work; and, of course, they are random variables pulled off the internet, so I cannot recommend applying them, and if you do, please use appropriate caution.

Does anyone know if it's the public 24fps patch that they applied?

i mean the immi101 i76fix ( https://github.com/immi101/i76fix )

This was the cleanest fix to apply for me. If it's now patched with this, great!