Hmm, I wasn't even thinking about fuel efficiency, but that's interesting.

I meant, for anyone that missed it, that commuting by bus/train/tram/metro is much more common in urban areas in Europe than in the USA.

Compound that with driving more and it's a lot more time spent filling up.

Wow! Average 57 mpg in Europe - really? Even for diesels, that sounds extremely optimistic; is that from manufacturer-supplied figures?

US gallons happen to be smaller too, fwiw

Well, my 7 years old Mercedes A 180 CDI 2012 model (Diesel engine) averages 53 mpg (4.4 l/100Km) still today (see my old comment with all the details for the these numbers at https://news.ycombinator.com/item?id=14552816). The manufacturer-supplied official numbers are even better (3.3 to 3.6 l/100Km, or about 65 to 71 mpg).

NB: the above mpg numbers are computed using US gallons (3.785 litres)

Useful economy figures, for sure. It's the average across Europe that I'd find really surprising, given how many older vehicles there will be, and not all diesels