All in the topic really...

Most obvious in the TV view. See my car in attachment on the start and in the finish (1 lap race).

SPR is version W10. But it's not really W9/W10 issue, it's been ever since the sound optimization came ages ago...

LFS only plays the sound of so many cars, maybe 12 iirc? Im not sure how many, but i remember it being announced in patch v i think. If your car is in the back of the pack your cars sound wont get played, because it will play the closest 12(?) car sounds. those being the ai cars in your replay.

EDIT: FOUND IT!
Changes from Version U to Version V :

Sound :

Improved car engine and other sounds, added gear whine etc.
One extra car sound is now played (now 5 including your own car)

Its only 5, not 12.

it says it includes your car, im guessing at all times. Unless it is out of the sound "drawing" distance. Maybe it is out of the "drawing distance untill it comes closer?

Quote :

One extra car sound is now played (now 5 including your own car)

I guess that was meant as in: when you're using the views intended for driving.

But if you're driving/spectating/viewing replay from the shift+u or TV view, sometimes it gets cut off because there's already maximum amount of sound generating cars.