I would think that a M3W would be just as safe as say a Miata would be, so they don't require a helmet for a sports car that happens to be a roadster.
I believe you need to put down the koolaid.
Maybe a bit of an exaggeration, but the full perimeter tube frame work of the M3W should be quite substantial in an impact from the side or front, the rear may be a bit less structural though.
