BTW in the first video, I noticed a significant delay between when the car hits the wall and when you hear the impact sound.....
You get that with all sounds from the car, simulating the transmission delay through the air. Watch the car accelerate and change gear, but hear the delay on getting back on the power - you'll see it squat before you hear it take off again!
I quite like it, and it was already present in Prologue.
I've also been thinking about the reverb sounds again. It seems the volume of the reverb scales with the volume of the car itself (due to range, not just throttle position etc.) whereas it should be almost independent, assuming the car and listener are in the same listening space (i.e. not shielded by a few miles of trees, as is possible on the Nürburgring.) There should be a "global" set of channels for reverb, that is set according to the environment the listener is in, and all cars within that environment contribute to the (directional) array of reverb channels which are heard independently of the sources (cars).
The drawback to this is that it probably won't like sudden changes in viewpoints (and might be why it does scale with range), but they already handle the (above) delay mechanisms very well during camera changes in replays, for example (no doubt using some kind of trick).
The most annoying thing about the sounds, is when you for example lay your car on the fence, or a wall, and stop it there.. it will make constant bangs like someone is panickly banging in the trunk

What's up with that?
That repeated banging is a classic instability with collision physics in almost all games - it can be tweaked out, but I'm sure it's tricky without enforcing some strict rules on stopping motion / interaction after a preset time, e.g. the Source engine's implementation of Havok - this is not really plausible in a racing game, though! Except the cones, maybe. It's annoying, yes - prior versions of GT never did it (except for car-on-car, but that's different), but then prior versions all had terrible collision physics!
