[Merefield]

... for my taste i prefer more colour contrast.

For me, in a country with not particularly great sunshine, i prefer an interior with more colour, or more contrast.

So, i'd go for a red or walnut interior with this grey. For me this makes it more "jazzy" in keeping with the spirit of a sports car. The Z4 to me is no shrinking violet, so don't hold back on the interior colour in my view.

I'd have black before ivory too, but again, that's just me.

All a question of taste ...

I'm sure you'll love it whatever the combo, its not like BMW will let you specify a bad one!