Alright, so it's not an M-Car, but we have this as a pool car at work, and I borrowed it overnight yesterday. It's a fully electric demonstration vehicle based on a 1-series coupe - was never in full production, but used to prove systems for future cars, kind of an extended field test.
http://en.wikipedia.org/wiki/BMW_ActiveE
For use as a town car, it's actually bloody good. 0-60 in 8.5 seconds, and the electric drivetrain gives it instant throttle response and full torque from rest, so it feels fast enough. The steering's pretty heavy, and you can feel that it's a heavy car (1800+kg!), but it's actually quite fun to drive, and it handles OK. It's totally silent apart from a slight whine when accelerating hard, and tyre roar.
I guess we'll probably see one in Munich somewhere...
BMW 1-er ActiveE by
tw_tvam, on Flickr
One of the batteries by
tw_tvam, on Flickr
Energy display by
tw_tvam, on Flickr