I must say that the lighting in GT6 is ABSOLUTELY PHENOMENAL! Last night me & a mate were mucking about with the time settings on the long Nurburgring tracks, setting up sunrises & sunsets etc, & OH MY GOODNESS IT LOOKED AWESOME!
Best to experience it in the KTM X-Bow in car, as you see the sun glinting off the body work & you get glare in the mirrors, plus you see all the sky. My mate was getting really freaked out as it looked so real, he's never seen day to night transitions in a sim before. The sheer scale of contrast is EPIC! The clouds in the sky went from white, to peach, to pink, & the sun goes from yellow, to orange, to red, as it goes down. Everything just looked so tasty.
Then we set up some overcast conditions & savored the excellent mist/fog effects. WOW!
I think that experience right there was worth the £39.85 I paid for the game. 
EDIT: In the above post I was referring to the 1.03 lighting effects. After the 1.04 update they have been "altered", & are no longer exactly the same.
Last edited: Feb 14, 2014