A few choice quotes:
This started with GT5 Prologue, and was the start of their new approach to recreating sounds in the game: simulation. Never mind recordings, this part is very important no matter where you get your sounds from, and it'll really shine once the sounds themselves are improved. He missed the part about correct transmission delay and atmospheric attenuation, though.
This is dynamic range compression, also present since GT5 Prologue. It was tweaked in GT5 and the default, low dynamic range setting (living room) caused dramatic level changes when loud cars or tyres drowned out the player car's engine sounds.
I've said before that the "dynamic range problem", as I call it, is only half fixed by offering a dynamic range option (in the form of a level limiter / compressor): you need a switchable mixing scheme as well, in order to balance out potential spikes before said limiter and keep everything close together in the mix. There are psychoacoustic considerations to follow in achieving a full solution, and getting that into the game would help with adding even more sources at some future point, because then you have a way to know which ones you can "switch off" with minimal impact.
It's more sources the game desperately needs.
He put this in the part about recording cars, but really there's little left to learn on that front. This is about the previous point:
That's where you need to unravel the mysteries.
Throw in the mystery of the Red Bull and Senna cars, and things get a little more hazy; why no mention of these specifically improved sounds? All things considered, I think it's clear: he's teasing us again!