I posted this announcement some time ago on Car SpyShots before I was banned for some reason
But at BMW we test everything to find the solution for our requirements.
The original testing prototypes of the E93 were engineered using various options and configurations - We used conventional canvas roof , Carbon Fibre, Aluminium , magnesium before settling on the lightweight steel used on the production E93.
The decision day is fast approaching to which material will be used to accomodate the M3 Cabrio , BMW are requiring an offset to weight similar like the M6 Cabrio which will not cause severe penalty on the M3 dynamics. even though our studies show that the M3 Cabrio are mainly bought for looks than for outright performance.