Considering how many little things we keep finding out about (bonnet/hood view, backfire.. these things aren't even in our "latest" demo), it's quite likely the sounds may surprise us all, being far better than anything we've anticipated or heard so far.
From what I have noticed in GT4P, each car has its own sound. The Delta and the Woodone Tom's Supra sound incredible. Especially the Supra.
Just go to the official GT4 site (like Phantasm said) and there are 3 car sounds in there that are all differerent. There have also been several threads about sounds and I am sure there are links to some of the exhaust sounds in there as well.
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