Finally, a sensible comment, a couple of other things to add for non-UK residents:

Fiestly is how well maintained cars need to be to pass the regular MOT vehicle checks required to drive on UK roads, so even if someone is driving a small 2000-2010s diesel (as was recommended at the time) it's not belching clouds of smoke, and is generally mechanically pretty healthy.

And secondly how a large proportion of the vehicles affected by this zone-embiggening are actually vital secondary modes of transport for families who already primarily use public transport. I grew up in (an admittedly better-connected suburb of) London and while most families made use of trains/buses/tubes for commuting, school, and habitual travel - they all had a small/medium sized car for ad-hoc things like a big weekly food shops, transporting bigger loads, and all the routes that are just plain bad to do on public transport - London's rail is a hub and spoke model which sucks more the further out you go (trying to get from spoke to adjacent spoke).

Now almost all of those families, who have been carefully maintaining their car for the few trips they need (including those who's kids have flown the nest) need to buy new cars to continue.