The Z4 is just horribly NASTY! Front, rear, side, that car has NO good angles (and all together too many clashing bad ones all over the place).
I actually saw a Z4-based M-coupe today. It actually wasn't as hideous as either the original M-coupe or the Z4 roadster, though still far from any sort of attractiveness.
Keep that fiance! She's got the Corvette set dead to rights.