For me, my most dreaded track and, at the same time, one of my favourites, is the Nordschliefe. I love the combination of slow hairpins, long sweeping corners, fast straights and all the bumps etc that unsettle the car. Get it right and it is the most rewarding track in the game.....but, get it wrong and you will throw the controller in frustration, especially if you are leading the race and then mess up the high speed corners at the end and lose......all that work ruined in the space of 5 seconds. The race I am dreading most currently (even more so than doing the Red Bull at Goodwood) is running the Rain Masters race at the Nordschliefe....the satisfaction of completing it will be immense but the fear of getting it wrong and losing because of one mistake is severe....think I may leave it till last!
A mention also goes to Batthurst...it is an enjoyable track with it's narrow width, technical corners and long straights but it is not very forgiving at times....get it wrong and you are punished but get it right and you have a smile on your face.
Those are the only ones I dread, yet I like both of them for the reasons I dread them. The rest of the courses just don't have that same feeling of "Get it right and grin widely....get it wrong and cry about how life is cruel and how you have to buy a new controller". Let's hope for GT7 we get more of these special "Do or Die" tracks and less of the sterile ones that neither thrill nor terrify