I don't know if I'm the only one to think this, but I really am appreciating the attention to detail regarding sound design. I'm not talking about the engine/exhaust note in particular, but more about how they're emulating reality.
In almost all other racing games I have played, when a car travels over the curb you can hear the tires and curb interacting, but that's it. In GT Sport you also hear the chassis stress and creak just as a real stripped racing vehicle would.
The transmission sounds are also impressive, although they still need to be mixed better. Such as how the sequential transmission in the Mustang gr.4 now clicks and bangs with each shift.
Even the backfire sounds are striking. It's not a single loud bang, but a combination of gurgles and pops.
I guess it's the little things that impress me.