Ed Doe - "the engine feels a lot more like it's straining at the leash if that makes any sense - just wants to be let loose at any opportunity!"
That sort of is what puts me off... the 3.0 is fast enough, do I want a car that is screaming at me to go faster (not least as I don't do track days and have no immediate plans to do so)?
Zedebee - "You missed a pretty big elephant off the “con” list, that is they cost significantly more to buy." But other things being equal you get more back when you sell, so it's merely a question of whether the cashflow is high enough to have £15k tied up instead of £7k
"Until you are ready to commit to a well sorted (and reassuringly expensive) car, then stick with what you’ve got." 100% - maybe in a couple of years... unless I end up taking a chance on a real cheap dodgy one...
Mr Tidy - "it's all about the soundtrack, 8,000 rpm red-line and sense of occasion every time I drive it". Again, the thing that puts me off is the idea that the real benefit comes with your foot to the floor... do I need a faster car than a 3.0 full stop, let alone one that is begging to be revved to hell and back.
Plenty - "While I'm spouting unpopular opinions, going from an 3.0Si to an Z4M is, um, a bit boring I'm afraid. There are so many interesting cars out there to experience - why replace an E85/6 with another E85/6?"
A very fair point of view. But for me I love the Z4 coupe shape. Two seater modern(ish) alternatives aren't appealing - never been a big Porsche fan and a lot of them are expensive... the Japanese stuff doesn't massively appeal, not getting a Merc, TVRs are more expensive again. Aston Martins are too expensive and too large.
I could get an Evo or Impreza, but I want a two seater RWD sports car really. Ideally significantly bigger than an MX-5, but ideally a touch smaller than a Z4C in preference to any bigger.
Z4MC makes sense on the basis that it's half the price of a TVR 350C and I don't wanna porsch or merc or 370Z and Astons are too big.
I suppose the answer to the question is "because a Z4MC is a perfect half-way step to £30k of TVR coupe from a similar time."
The other answer to the question might be... you have a massive point, and maybe I should be saying to myself "the Z4C scratches the modern, fairly practical, almost-classic" itch... forget another modern-ish coupe... next time go for a Caterham 7 or a 60s or 70s TVR or Marcos or Lotus, something very different again.