The same publication even reports that BMW’s CEO Norbert Reithofer is not yet sure if he will be giving the car the much awaited green light to production. M division's CEO Friedrich Nitschke on the other hand is in favor the car and has plans to tweak the i8 sports hybrid so that an M8 can also use the same carbon fiber and aluminum underpinnings. In terms of weight savings and cost efficiency, this will be a very good move for BMW.
The BMW Z2 Roadster rumor has been circulating for quite some time already but the publication reports that the compact roadster has been cancelled.
For the time being, please take these rumors with a grain of salt. BMW has not released any official statement about the rumored supercar or the Z2 roadster.