digdugdirk has the right idea, and AFAIR, there is some work on that front (https://www.fornjot.app/).
Also the Fiat 500 goes 100km on about 4l of gas, while the Ford F150 uses 7l. No clue where the author gets the idea that the Fiat would get worse mileage, perhaps he's dividing by weight?
The rest, I don't even.