It's a well-known fact that the automotive press has run out of superlatives for the BMW 3-series lineup. In the case of the M3, the ultimate 3-series, the praise is typically amplified. Well, not so much for the convertible M3. You see, the automotive press has a penchant for very odd vehicles the general buying public simply doesn't understand, so we tend to eschew the cars "normal" people want. As a member of the press, I'm required to beg BMW for an M3 wagon instead of this goofy M3 convertible. The truth is, neither model makes much sense.
Chopping the top off a car doesn't do anything to increase performance, and it almost always reduces performance. It's very difficult, if not impossible, to maintain torsional rigidity without resorting to a bunch of heavy braces. Even then, most convertibles suffer from some degree of cowl shake, and folding hardtop convertibles, like the BMW M3, are prone to squeaks and rattles when the top is in place. Granted, Michigan's roads are particularly harsh on convertibles and most convertible buyers hail from warmer climes where the roads are in much better shape.
Ignoring my personal feelings that convertibles, like sunroofs, are a complete waste of money, the M3 convertible makes sense in a one-up-your-neighbor-at-any-expense sort of way. When driven on a public road, the M3 convertible will do anything the M3 coupe will do, plus the top can come off. There's no real value to this trick other than doing something your neighbor's M3 coupe can't. To some people, that's worth the $67,325 cost of admission. For these people, money is probably not a concern and it wouldn't be impossible to have an M3 convertible for cruising down the coast and a serious track toy in the garage.