i dont think tan looks bad with any color. afterall, it is a more natural color for a leather interior.
i have a friend with black and tan and i like it. ive seen red and tan and i like that too.
i personally think the color of the interior has the most impact on black cars. (andmaybe white also). my black and black really de-accentuates the interior cockpit and it is all exterior that you notice. you get some 'bleed over' from the interior asthetically, as the interior kind of blends into the car and actually competes with the cars lines from some angles. my friends tan interior black nsx really seems to beckon you inside, as the tan stands out against the black body.
maybe its the pasture greener syndrome, but i actually prefer the tan interior with black or red. however, for the typical buyer i do not think there is any difference. my observations only come after numerous hours in my garage, which a new nsx owner has yet to experience.
