electric cars/minibuses max permissable weight

[Glasgowrob]

i'm vaguely aware that theres an increase for EV or alternative fuelled vans so somewhere around 4200kg but seems the same extension doesnt apply to cars and b licence minibuses

hit with a thought earlier looking at some of the newer electric stuff, its bloody heavy ie the Mercedes Evito comes in at 2860kg with a GVW of 3500kg
maybe i'm missing something here but a small minibus designed to carry 9 passengers including driver and perhaps a bit of luggage only having a payload of 640kg seems a bit off either that or i'm going to have to go on a serious diet if we ever add one to fleet. compare that to something like a 9 seater vivaro diesel with a payload of nearly 1200kg unless i'm missing something its not fit for purpose.....