The original Honda Insight from 2001 got 68 highway, 60 city. And it had all the goodies you’d want in a “modern” car like airbags, aircon, heat, 2 relatively roomy seats, etc. Close to the Doodlebug’s best possible mpg with twice the passengers.
Unfortunately, after 20 years of improvement in auto design, material science, etc, the new Honda Insight in 2022 actually has notably worse city /highway mpg from the original, because it’s so much bigger.
I guess my point is all the innovation in the world won’t fix the fundamental problem that people want bigger and bigger cars?
I got to see one at a Stellantis exhibition here in the US! Although they won’t be sold here, so IDK why they brought them to a US event. They’re such neat little cars.