I'm of the belief that sound is as important as anything in creating immersion - and I've found some of the cars' sounds ingame don't quite match the experienced RPM. While I'm very impressed with t...
Ideas
Interesting post. May I ask how the "it sounds like it revs xxx in game" is determined? Is it just by ear/feeling?
There's two cars in particular I think sounded much better in previous games, esp from the interior. The M3 lacks "punch" in this game and the Fiat 131 is underwhelming as well. The latter almost sounds like it's misfiring at higher revs.
Certainly - it's got a lot to do with harmonics and frequencies. I'd recommend reading these articles for a more detailed description - but a given engine layout will generally make the same pitch at the same RPM as another engine of the same layout. To a degree, this also applies to cylinder counts - 2, 4, 8 and 6 cylinder engines all produce common frequences at the same RPM, as do 3, 6, and 12 cylinder engines etc.
To a degree it's by ear because once you learn what the correct pitch "should" be, you can make estimates from there - but there's also a mathematical way (outlined in the formula in article 2):
(rpm / 60) * (cylinder count / 2) gives you a base dominant frequency, which the engine's pitch should match a multiple of at the RPM used in the calculation. Here's a worked example for the Citroen C4 (which is correct ingame):
Redline rpm = 7500
7500/60 = 125 hz
125 * 2 = 250 hz
At 7500 rpm ingame, the C4's engine sound has the same pitch as this dominant frequency, so the pitch is correctly scaled to the RPM!
This writeup actually inspired me to go back and record all the inaccuracies in a spreadsheet; I went back and re-checked all of them while I was at it and have updated values accordingly.