Watch a UK motoring show called Top Gear if you want to understand the mindset.

Physics is a footnote. No one needs a car that's bigger than a mid-range family hatchback.

There are tiny justifiable markets for people who have to off-road for a living, like farmers. But those are a footnote compared to the car-owning mainstream.

So there is no practical reason why emissions can't be reduced to 140gm/km, or much less.

What has to change is the primary function of cars - which isn't to get people from A to B, but to indicate social status and class.