BMW have some serious bad luck with timing when it comes to supercars.
The original M1 also never accomplished its original mission due to financial difficulties at Lamborghini, which was also sort of a last minute curveball for BMW.
It's a shame, really. I've always felt that out of the big three German automakers that BMW had the best potential to make the most capable supercar of the three had one ever come into fruition after the original M1.
Even after the failed deal described by Gordon Murray, there were still missed opportunities over the years from the 2000s with the S65/S85 engines to more recently with the i8 chassis/CFRP production.
In an alternate universe: