The engine sound system is sample based, but they are small samples which are then randomised using some algorithm. I don't know if there are different ways to construct the engine sound relative to different conditions. This was mentioned on the member's forum a long time ago, but I can't find the details now, I don't remember the specifics.
As for not feeling the tyres on the track, I'm surprised at that opinion; it feels very connected to me, more so than any other sim. The tyre model feels great. There's a real feeling of 'bite' and you can hear the tyres chirp as they get pushed.