I had a red interior in my Mercedes C class, it divided opinions but generally was applauded.
I also had red in my second RC, similar comments again
I think a red interior is a statement and one that you must feel comfortable with...
How about a Hazel or clove colour interior as I had in the red RC, I think it would go well with a black exterior, quite classy?
I found the red did take a bit of looking after, depending on one's daily attire but nowhere near a much as the clove. Black does have it's advantages!