I visited an OEM car manufacturer who had a few prototype electric vehicles. The main gearbox was replaced with a brushless DC motor and the engine bay had a big bank of LiIon batteries. It could be charged from a 13A UK socket.
Did you see the episode of Wheeler Dealers with the electric Maserati Bi-turbo? Basically using off the shelf components? It's here if you haven't
100-150 mile range would turn a similar P6 into a practical and fun commuter and shopping car.
It did seem a bit compromised as it drove the conventional gearbox which seems unnecessary and also a weak link with all that torque going through it - I assume some sort of moderation of this must have built into the control systems. Dead weight also.