DG/Rangie: it's seldom thought out sensibly - there's a mixture of a commercial car industry (including new/used sales, servicing, parts, fuel, and so on) which largely works by supply and demand AND government regulation of the design and use of the product (which has nothing to do with supply and demand).
We still have massive choices - new, used, lease, hire, switch makes, keep existing car, trade in, swap on ebay. These all have different costs and benefits.
Conflicts appear if, say, I'm still running the MV6 and my local area becomes a ULEZ or they alter the VED bands again. Then I'd need to choose between the additional cost against changing cars. I might choose the additional cost.
But I think it's important to keep that choice and keep governments out of it as far as possible, even if the intentions are good. Or it could end up with being told when and which Trabant you're allowed to have.
None of these things have easy answers:
https://www.youtube.com/watch?v=-_gU50mfehIhttps://en.wikipedia.org/wiki/Ford_Pinto#Cost%E2%80%93benefit_analysis,_the_Pinto_Memo
