I don't know about Tim, but we started this coversation about Luigi.
1st of all, all respect these fast guys, but... Dunno if you take your time to try Luigi's "setups"... why i put it between ""? because it is not a real setup, what he does most of the times, he just makes tha car as soft as it possible, with relatively high wing setings. So anti roll bars softest front and rear, springs softest front and rear, neg chamber almost as high as possible, and ride hight as low as possible... nothing else, no gear ration, no bump/rebound, now tow in, no diff changes. So i tried his method. Loaded Spielberg, run 10 laps on my setup, all 10 laps within 2-3 tens, close to my best. After i changed it to his setup, and on the first lap i did a 4 tens better than ever. Also one of the DTM competition leader/winner gave a hint not so long ago about his lap, and he said high wing setting with very soft car.
So again, all respect for these guys, Luigi is still more than a second infront of me on Spielberg, no doubts that he is talented and commited to racing, but it seems for met that the secret is in the physics engine as well, which looks way too simplified in this aspect.