LGM,
As far as we know, no one has done that modification. One needs to be a rocket scientist or at least an electrical engineer to even attempt it. Maybe GlennD has looked into this question. It is too bad that MB ended the B250e program as it is a nice sized full featured car rather than extend its range. One of the rumours is that the GLA might be turned electric and it seems to be only slightly larger and more streamlined. I could roll into that in 2020.