I normally use 82 but thought I'd try out 40. It's so much cooler on 40, you can get right up to the back of other cars, just have limited view and the car appears to turn a hell of a lot faster.
I am using a 110% Fov on a 100 inch screen with a resolution of 1920x1080p (in the Volvo). For some other cars i am changing the Fov to a smaller one (90%). Ill never use the virtual rear mirror so i always need to see the left and top mirror.