Always disliked Le Mans in iRacing. Slowdowns every corner, and the ford chicane at the end of the lap is just one of the worst corners out there. 

I started to build the setup on lowest wing, but quickly noticed it just wont work as the car was really loose everywhere no matter what you did. Going up just a bit on downforce really helped, and it does not cost you too much on top speed. I also tried to compensate on top speed elsewhere.

Audi seems to be just fine here. The issue of the car is that the car feels very stiff no matter what you do compared to the Lamborghini. That's really noticable on the ford chicanes at the end of the lap. You cannot take the kerb as much as you would want. High speed grip is good as always in this car.

Here is the weather used: