That's the same color combination I have on my 2010 IS250. You'll love it! I get many compliments on this color combination. By the way, the exterior color is like getting two colors in one - at night ,it looks like a dark gray metallic, and in the sunlight, a dark charcoal metallic! Nice.
By the way, the carpet on the IS is indeed darker (not the khaki color) - looks nice.