Just had to join in this thread, couldn't resist and I know I will get flamed LOL
I ran a Z4M for a few months, bought it with 4000 miles and sold it with 12,000 miles. I've had half a dozen 350zs and a Boxster, and don't get me wrong I LOVE the 350z. I just got back from a thrash around the Scottish highlands in a 350z roadster and loved every minute of it.
But I'm afraid I have to say the Z4M was in a different league.
Seriously. It cannot be compared to a 350z or a Boxster. It wipes the floor with them both. The 3.0 litre model is a more direct comparison, the M is not fair competition.
The M is focused, rapid and very very capable. In terms of power and handling it's a definite step up from the 350 and the Boxster. It would be perfectly at home on a track and I regularly used to upset blokes on big motorbikes down country roads - I know how upsetting this can be because I'm a biker myself.
It looked awesome, sounded awesome and the Stereo ( 400 watt DSP ) was the best I've ever had in a car and makes the 350's Bose sound like an Amstrad. I was once sat at traffic lights with the roof down and a pedestrian approached me and asked me if I was Batman !!! ( My car was Black with Red Leather ). The traction control was flawless and saved my bacon on more than one occasion where I got slightly over enthusiastic !
For the record it averaged 26mpg over my period of ownership, so not a lot different from a Z and it didn't need Super Unleaded either.
The only thing I don't like about the Z4M ( and all other M sport BMWs ) is the stupid fat rimmed steering wheel they insist on fitting. I have average sized hands and I find these thick wheels very uncomfortable to hold.
Out of all the cars I have had recently I miss the Z4 M the most and I will definitely have another. Serious piece of kit, a proper tool as they say.
P.S. For those who say they are too common - I never saw another M all the time I had mine. Very very few around and makes you feel very special when you see a 3.0 or 2.5 - usually reversing towards you at a high rate of knots
And they do look quite different to the lesser models when you look properly. The arches are more flared, the wheels are much wider especially at the rear and of course 4 exhausts. I would recommend anyone even remotely interested to go and drive one. You will want it