The whole argument that "the best car to drive is the small old efficient one you have today" always seemed idealistic and false on its face. Sure, lifetime emissions of that vehicle are likely lower if you ignore the initial cost of that vehicle... But it's not like the option is between "scrap the old efficient ICE vehicle and buy a new EV" or "drive this old ICE". That older car gets passed on to another consumer, who will, likely, on average lower their total emissions.
New vehicles are inevitable, as older vehicles are eventually infeasible to repair. So, the correct answer is to actually look at lifetime emissions of a vehicle... You can never ignore that initial cost to manufacture, even if you current already own it.
The only way you actually worsen lifetime emissions is if you somehow hoard cars and cause repeated "initial manufacturing emissions" in excess of a typical consumer. Everything else is just moving when you count the consumption.
New vehicles are inevitable, as older vehicles are eventually infeasible to repair. So, the correct answer is to actually look at lifetime emissions of a vehicle... You can never ignore that initial cost to manufacture, even if you current already own it.
The only way you actually worsen lifetime emissions is if you somehow hoard cars and cause repeated "initial manufacturing emissions" in excess of a typical consumer. Everything else is just moving when you count the consumption.