Decarbonisation requires fewer cars and can't be achieved just by electrifying current numbers of vehicles. So we need to electrify public transport, freight, services, car club vehicles and taxis, and provide for individual car ownership where alternatives are impossible, but otherwise we need to drastically reduce the number of private motor vehicles.
A 2019 Parliamentary report "Technologies for meeting the UK's emissions reduction targets"
"In the long-term, widespread personal vehicle ownership does not appear to be compatible with significant decarbonisation. The Government should not aim to achieve emissions reductions simply by replacing existing vehicles with lower-emissions versions."
A report from the Low Carbon Vehicle Partnership found that:
"a typical medium sized family car will create around 24 tonnes of CO2 during its life cycle, while an electric vehicle (EV) will produce around 18 tonnes over its life. For a battery EV, 46% of its total carbon footprint is generated at the factory, before it has travelled a single mile."
The carbon emissions of vehicle manufacturing will reduce as the broader economy decarbonises (Australia will eventually start decarbonising iron ore mining, for example), but this is going to be a slow, steady process, and the problems with sustainability are broader. Manufacturing multi-ton vehicles is resource intensive and it seems unlikely that will ever change.
And global equity considerations make it even clearer that anything approaching one motor vehicle per household is unsustainable. The UK has roughly one private motor vehicle for every two people; the world as a whole one for every nine people. Are we going to demand more than our share of the world's resources here, or do we envisage the manufacture of three billion new vehicles?
What are the implications of this?
Families who have already managed to limit their car use to occasional trips, and who mostly use public transport or walk or cycle, absolutely should not be buying electric vehicles. They should be keeping their old cars going as long as possible, until they can give up owning a car and switch to using car clubs, taxis, and hire cars instead.
And governments, national and local, should focus on reducing car use rather than electrifying private vehicles. Getting one vehicle off the roads - and one fewer vehicle manufactured - is the equivalent of electrifying several. Electrification efforts should be concentrated on taxis, car clubs, buses, service and freight vehicles, and so forth.
See also: "The Solution is the Problem"