Most people in London don't have cars. Especially those living in flats and blocks.
Or just keep driving the diesel/petrol car they already have - no one is banning the use of existing cars after they ban the sale of /new/ cars.
(I am a non driving Londoner and it's pretty good. I don't think I'd feel the same way in many other places)
Take a look at https://www.ons.gov.uk/census/maps/choropleth/housing/number...
In Birmingham, about a 3rd of people have no car. But if you zoom in to central, it's about 2/3rds of people have no vehicle.