offensively poor fuel economy from most vehicles on the road
Hmm not as bad as you think. My wife’s old 2l Ford Escort got about 35mpg on long trips which is about 42mpg. When you consider it was automatic, that’s comparable with late 90s engine technology here.
Mid to high 30s is common for sensible cars there which would be around 45 here, which many people consider respectable from petrol cars. The reason diesel is not popular is because they couldn’t be sold between 1997 or so and the late 2000s due to smog regulations. When hybrids were released giving diesel level economy with petrol level NOx emissions they sold like hot cakes.
Of course, lots of people choose to drive huge trucks, which is another issue. It’s amazing how environmental concerns are completely off most people’s mental radar. It just doesn’t occur to them that they are doing anything bad at all.