The question is, if I’m buying an oldish s/h car (which has already been made for somebody else to use, and it’s not desperately environmentally friendly to scrap it), given I do very little driving in congested cities* is it not actually more environmentally friendly for me to buy a diesel rather than for somebody else who does more of that to buy it instead?
Clearly the same argument may not apply to those who want to spend lots of money every month for the privilege of owning a new car – personally I’m looking forwards to huge depreciation on diesels 😉
* I do regularly drive into my most local small city and town but not at rush hour and very rarely meet any congestion. You’ll have to excuse me for only a vanishingly small amount of guilt at doing that in my diesel given all the other far more polluting diesel vehicles on the road when it is far more congested.