Briefly. Every sim is realistic inside its own physics bounduaries and capabilities.
As JeffR said, the real world goes down to the level of molecular interaction.
Yes, it would be cool if the sim engine could load different objects made of different "materials" and simply make them interact under the known laws of physics. We could have car engines made of the same number of parts as in reality. But this is a job our PCs will not be able to do in real time, nor the most powerful of worksations... maybe a cluster of servers could make it. Maybe.
So, we have to accept the compromise and enjoy the sim that gives back the best feeling, which is LFS (
).
Another thing are the g-forces. We don't feel anything except for steering feedback. So we don't feel the back sliding out whith our.. back (
), as occours in realty, nor we feel the consequences of a crash or many other sensations. That leads us to push the limits way beyond a real racing driver would do. If you whatch any top 10 hot lap you'll agree with me.
We race in a world that is different from the real thing, and this world has its own realism. A very close approximation but actually different. Not better, not worse. Just different.
IMO.