Well I'm still a newbe, but it was very interesting to follow this discussion and I hope I learnt some proper behavior. In particular trying to let someone a car width room, if he tried to force you to slow down before a corner, seems to be very sensible.
My experience with good racing simulations is almost constraint to the multiplayer demo of LfS for 4-7 round races. So I have some questions, too.
If I'm racing with the same guys for several races and there is somone who is about 2 seconds faster than me per lap, shall I let him pass, or give him a fight for the position? Guys who are much faster than me can overtake me inside 2-3 corners without problems. If they have the patience and don't kick me out the 1st corner, claiming me of braking too early. I don't complain much about such things, instead of this I try to change the set-up in order to brake later, if that happens to me several times in the same corner. Nevertheless I find it unnescessary and dishonorable for the better driver.
But if someone is only a little bit faster, there is not much he can do, as long as I make no major mistakes. Sure it could lead into a crash, if he tries to force me to slow down before a corner, but, hey that's racing! Or is it a wrong attitude?
Nevertheless in the beginning or middle of a long run race I would properbly pass him without much resitance, because it makes no sense to ruin the lap times of both drivers, giving other players the chance to hang on.