Avus Blue is discontinued and has been replaced by LeMans blue which is darker (see previous posts with pictures of 2001 models). I feel LeMans blue is superior to the old Avus Blue and one of the best M5 colours (my other favourite being Carbonblack).
I saw my first M5 in Avus Blue at the San Francisco Auto Show last year and fell in love with the color and car. Ordered mine and settled on LeMans Blue and I'm delighted.
It is about 2 shades darker and "richer" looking and goes better with 2 tone interior if you choose it. I went with black leather and dark wood trim and have no regrets. I constantly get compliments on the color.