Yeah...that one was hard, it took me a while but i got gold in the end.
What you do is drive through the course untill you get to the very last corner before the long straight. Now, wait there until about 3 or 4 cars pass you, what your really waiting on is the dodge viper to come, once it does, stay close to it around the corner and slipsream it up the straight just before the starting line which gives you the boost you need. Now all you need to do is try and controll that bloody GT around the track which is a hard task on it's own. Hope this helps!