[ppf]

The Fiat 500 from 1957 got 43mpg. Imagine what could be done, if car manufacturers were not focussed on the lease market, meeting the newest emissions regulations (more relevant in Europe), and filling cars with electronic toys.

[user-the-name]

Renault Twingo III gets 66 mpg, while having much more space and being generally more useful.

[ppf]

Yep, there are modern engines that will do that. I was using the example of an older engine, because they are generally much more fixable (which was OP's original point).

[busterarm]

But it's so much more complex than the 50+ year old Fiat 500 that the home mechanic can no longer work on it.