>>358482396
This is a really interesting question. Ideally, you'd use an ambisonics FX chain to split the original stereo channels, simulate their locations in 3d space, apply a convolution reverb measured or simulated from inside a car, then render the ambisonic signal back to binaural stereo based on your headset position/rotation. Unfortunately I haven't found an easy way to do this. You can theoretically do the ambisonics part by using https://leomccormack.github.io/sparta-site/ hosted in reaper (or jack/carla, or ardour), then patch in the VR headset pose using https://github.com/BarakChamo/OpenVR-OSC , but it's a very fragile setup, reaper isn't really a nice music player with playlists and all that, and AFAIK nobody has actually done the mapping between openvr-OSC and the input format sparta's spatializer expects. Maybe I'll try it myself sometime.

However, I did find you can use VLC's built-in spatializer (Tools -> Effects), which will at least make the audio sound like it's coming from speakers instead of inside your head. Combined with some of the EQ to cut out mids like your usual cheap car speakers, it actually sounds okay. It won't track your head, but it's better than nothing.

If you need to use streaming services instead of local files with vlc, https://sourceforge.net/projects/equalizerapo/ can work for EQ and a convolution reverb, but it crashes when I tried to use it with the sparta VSTs (or carla) . Plus you'll have to be careful to only play the music through the EQ and not the game audio. But may be worth a try as well.