True! Sound is more important that one might think, especially in a car game. Sound effects are great, even if after this patch they have decreased in detail a little bit. The problem is the sound samples.
PD doesn't even need to go and record more cars and digitalize the sounds and all that crap. It would be more than enough if the rearange the samples that the game already has so every car has a sound that matches its engine type.
It's not that complicated. They've actually done it already. Listen to the V8 Mercs. Remember how they sounded in GT4? Not a single V8 Merc sounded like a V8. Now they all do! There are 5 or 6 V8 Mercedes that have the exact same sample, but it's great because they sound like they should! These Mercs also share their sample with the Street M3 GTR, which sounds amazing!
Can't they do that with other cars that don't sound right? Of course they can! Having a couple of random cars that share their sample is better than having a bunch of V6 cars that sound like they have 4 bangers.
This might sound stupid(and it is), but to this point, PD should release a sound tuning option were we can choose a sample from the hundreds of cars in the game and put it in any car that we want. Come on, PD! If you won't fix the sounds, at least give us the option to do it ourselves.