Heard BMW is going to have multi-sized battery cells in the future. They'll be of different sizes, ranging between 60 kWh and 120 kWh, and of different shapes so you won't have weird electric coupes or sedans that sits too high. I'd assume with how flexible these things are, they could be used in the new Mini EV as well? But they won't be ready until 2021, so that may be too late for the first gen Mini EV.