1: Head to this link: https://github.com/doitsujin/dxvk/releases . This project apparently turns Direct3D into Vulkan (or something along those lines). It's meant for Linux, but in this case it also helps prevent crashing on Windows.

2: Download the latest release. It'll look like "dxvk-2.5.3.tar.gz", and it'll be listed in the "Assets" under the version notes.

3: Extract the file you just got (7-zip worked for me). You might have to extract twice, like I did (once to get the .tar file, once more to get the actual folder).

4: Go into that folder, then into the x32 folder. Copy the "d3d9.dll" file into your game's installation folder (if you're on Steam, that'll likely be "C:\Program Files (x86)\Steam\steamapps\common\Sonic & All-Stars Racing Transformed").

5: Once the file's copied over, that should be it! Just run the game like normal, and the random crashes should magically be gone.

6: Just as a note, I also set the .exe files to run in Windows 7 compatibility mode when I did all the stuff above. I don't know if that had any impact, but if the above steps didn't fix the crashes completely then this might be another thing you need to do.

All info in this guide was shamelessly stolen directly from: https://www.pcgamingwiki.com/wiki/Sonic_%26_All-Stars_Racing_Transformed#Game_freezes_mid-race