I'm not diminishing anything except people's apparent short-sightedness.
The Impreza in Prologue doesn't have the unequal-length exhaust manifold, as fitted to Imprezas of old. People in real life "complain" about the loss of the impreza throb on the newer models - although an owner on these forums did comment that the intake is still lumpy, as you'd expect, especially when modified. Trouble is, PD's sound guys don't "do" intake.
The sound engine itself
is important and it's doing a
lot more than simply placing sounds in a 3D environment. There's the tyre, wind, exhaust and intake tips, turbo plus ancillaries etc. etc. none of which (excluding blow off valve, where audible and squealing) are actually sample-based - the engine is computing it all in real time, as it should be. This is all added detail. I think the engine sound itself also has some"synth"; it's a common technique to put a pure-tone pulse sound under the samples to consolidate the sound and aid with phase alignment of samples. Perhaps this is too heavily mixed in GT, and a proper intake sound would definitely help here. (<-- LOOK a concession that PD isn't perfect!!)
By comparison, Forza's tyre and wind sound are pretty poor, and they don't separate intake and exhaust sounds anyway. And I've already said I don't rate Forza's attempts at "nailing" "pretty much every car" - since in actuality, they don't sound accurate either. That video is a joke, and anybody who thinks that's how those cars sounds in real life is not qualified to comment on sound in general! Take command of your brains, and actually
listen to it; rather than trying to
pick out similarities - focus equally on the
differences instead.
I've said this before, Forza manages, at best, a caricature of the sounds - notice how the S4 sounded like a generic (i.e. Nissan...) V6 when in fact, in real life, it sounds more like a Dino V6? These guys are not doing anything differently to PD, except using tried and true methods that mean they can get "familiar" results - irrespective of how flawed the method is, in terms of final results (all of the sounds have weird artifacts, in addition to those attributable to the "rpm aliasing" and they also whizz a lot more than I would have expected, and it still sounds like the engine isn't surrounded by anything...) That said, the Subaru and the Spyker (until it started moving...) impressed me the most. The Zonda was a laugh.
Saying "Forza is closer" automatically creates the bias in your mind that affects your perception (no, really). If I were to play an ambiguous noise and tell you it was one thing, you would focus in on that sound and pick out the parts that remind you of what I told you it was. At least, until I tell you what it actually is, at which point the previous similarities pale by comparison, since your brain now has a stronger association with the real sound, bolstered by your previous experience (the "oh yeah..." effect). Now that you have the correct reference, you can focus on where each example I gave is different to what you actually heard. Of course, our memory is usually biased / modified to some extent, so you have to listen to the real sounds almost repetitively.
You'll notice, if you do this sort of thing a lot, that after a while you become numb to it, and it "all sounds the same", which leads to the "vision" of that sound deviating from reality - not to mention some odd background fizzing in your ears, a bit like the audio compression on crappy YouTube videos - our inner-ears contain adaptive,
active "amplifiers". You have to take a break every now and then and come back to it fresh. In the context of game design, this means constantly flitting between markedly different sounding cars and taking lots of breaks from listening, to rest your ears and associated brain-bits. Could be difficult to keep productivity up that way - much better just to keep plugging away at it and risk the deviation in the artistic vision. (Actually: probably not. Do some resource management, or something, in between.) *1000
Now, you might argue that the thing that really matters is not whether it sounds exactly like the real thing, but rather that it convinces people enough that it does. But this is where my example, above, works in reverse: as soon as you present a sound which is more
detailed and more accurate to the real thing (assuming you've actually heard the real thing) then it immediately eclipses any other sound you'd previously held dear.
It's not all about samples, by the way, as both parties quite aptly demonstrate.
---------------
To summarise: Turn10 and PD do things differently. Technically, PD are miles ahead; artistically, both are flawed, but PD seem more anal (suprise!) whilst Turn10 will quite happily bend the sounds to fit their own ideals.
By the way, how many is "some"?
(Not my best post, but if you can battle through the awkward English there are some points in there somewhere...)