For those of us who own or are ordering/considering the 'vert (and who are tired of getting kicked around by the so-called purists - I say that to incite some friendly but spirited debate for those who are inclined to flame away), here are a couple of reviews that give some good performance data (these are a little old, but I haven't seen them posted on this site yet). These numbers seem pretty darn good to me considering the extra weight and diminished rigidity. 0-60 in 4.6 seconds, quarter in 13.0-13.1 at 107.9 to 109 mph, skidpad 0.86-0.92g... I don't think too many people would have predicted such good figures for a 2-ton M3 (ouch! - I have to admit - that really hurt saying that - and yes, a "2-ton" M3 admittedly does not seem too consistent with the "M" philosophy
I've owned my E93 for about 4 months now, and notwithstanding some of the less than flattering comments in the reviews, this is by far the most fun car I've ever owned (I think everyone else who already has one would also rate it very high on their own short-list for fun factor - but for those who are considering one but are not sure whether to get the coupe/sedan, my experience with having the drop top option more than makes up for the performance penalty which you're not really going to notice unless you're at the track). I recently had a full-throttle acceleration opportunity against a Maserati Gran Turismo from about 15-50 mph, with the Maserati about 1 carlenth in front of me - by 50mph (when we both came off the gas), I had actually pulled on him by about 1/2 carlength). So whilie the vert certainly does not embody the "M" philosophy like the coupe/sedan, being able to pull on a Maserati despite a +400lb weight penalty is not too shabby in my opinion...neither is a 0.92 skidpad result (which is better than almost any non-convertible, more structurally-rigid car you're going to see out on the road)...
Bottom line - I'm glad BMW has given us 'vert fans an opportunity to have arguably the best 4-seat convertible one can buy (at least short of $100k, whether you include the CLK63 AMG vert or not)... and certainly the closest thing a 4-seat convertible can come (at least at present) to what "M" stands for (don't get me wrong though, it would be fantastic if the next-gen M3 'vert sheds a few hundred pounds combined with even more than 414hp - I can't even imagine how fun that thing would be with the top down
Anyway, here are the reviews: