I missed a couple of things with the sound, but I think they happened well before 1.17 - I'd greatly appreciate if you could keep a listen out for them.
The off-throttle tone of the Subaru VGT is much more sedate now (which seems to be the linked to the exhaust popping in the newer cars, too), and the idle of the AES cars is not rock-steady like it used to be waaay back when, there's a bit of noise wobbling it about (and it shows up on the gauges, so it's in the physics, not the sound only).
You can probably verify the idle easily: good candidate is the RB Junior with its 4-digit tacho. The other change is just something you'll notice once you update, if it was changed in 1.17 (I think it actually came in 1.15, with the Mini VGT).