The strong interpretation of the GP's proposal is that such a system would include carve-outs for assistive vehicles.
This is just more middle brow intellectuals thinking they can make everything alright and solve the worlds problems when they’ll end up making things worse. If people can afford large vehicles then let them have large vehicles.
For people like us it means a market for used vehicles already exists and I don’t have to rely on the whims of some bureaucrat to approve my vehicle apportionment, comrade.