The Original Z4 was more a competitor towards Porsche boxter than the excisting Z4 is.
Why, because the former was supposed to be it's main rival, and build accordingly.
Now the excisting Z4 however, things were different.
This time around they targeted the SLK as it's main rival, making it less sporty, but more stylish, elegant and refined, hence the roof, and no true M model.
I thought the Z2 was supposed to be the miata/boxter killer?
What BMW needs thought is something SL'ish.
The 6 is not it, BMW needs some more uber premium convertible's!
3 series: E30: 89 325i, E36: 92 325iC, 94 320iC, 96 320i Convertible, 94 320iaC, E46: 99 320ia, E90: 06 318i Le mans, E91: 07 318dt
5 series: E39: 97 520ia, 01 530Dat, E61: 09 520Dat
X series: E83 05 X3 2.0d , E84 10' X1 2.0 X-drive DA.