I'm starting to learn that the alternative of seeing someone behind you trying to pass, and leaving room on the inside of the turn in case they try a pass, leads to a lot more enjoyment! 
Paul (Ibby) Ibbotson

I totally agreed Paul, sim racing is not like regular racing due to glitches that can happen when there is contact or lag.  It's always best for the guy in front to make their intention clear and the guy behind to do the same, so both can enjoy the close racing.  If in doubt always leave room.  I also learned that early in a race if the guy behind is obviously faster than you, it is often better to let them pass and then follow them which magically make you faster, so less chance of the rest of the field catching, as defending only slows you both down .