Yeah, the distortion idea was great up until they decided to use it all the time. I would only have used it over a certain threshold, to give a better impression of the dynamic range involved (you know, that horrid / awesome buzzing you get in your ears when you're destroying them).
We shouldn't underestimate the importance of sound, but it certainly isn't priority one, sure.
Actually, what I'm talking about is pretty fundamental. The very issue is what you call "believeable" - you can't convince everyone that what you've done to the car is reflected in the sound it makes, unless you record a car with those exact same mods. Not all cars have different sounds according to tuning state in FM4, some stay the same, like they did in FM3, so they have to sound "brutal" even in stock form. I'm talking about a change in attitude and approach to car sounds in games, to allow for greater flexibility in the sounds it can produce - cars are already being recorded as it is, so it's only a small extension to do that recording in a slightly different way to allow the use of some custom synthesis to reflect more changes in the game.
Realistic limiters, BOVs & wastegates, etc. are all easily fixed, too, and could actually compliment the variation in the other parts.
(By the way, the 312 T is a 180° V12 / flat 12, not a Boxer; I was really referring to the older 65° V12s, but they sound similar enough for obvious reasons.)
There are better ways of translating the raw power of the pressure disturbances these cars create. I've heard "supercars" in person and have been underwhelmed (when you've had your bowels massaged by a Top Fuel dragster, nothing else compares
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He's not wrong, though, it is exaggerated in Forza and NFS (of late) - I blame The Fast and The Furious, personally. If you want power from your games, invest in some serious hardware - believe it or not, the biggest impression a loud sound makes is full-body, your ears are next to useless - how do you re-create that without the health risks? It's impossible, so what you should be focusing on is the realism of the localisation (spatial positioning, reverb, etc.) of the sounds as well as the fidelity of any synthesis, in terms of both the method (neglected in most racing games) and the samples themselves.