Gary,
I think you are right about the mid-late eighties being the pinacle of fuel efficiency in US market cars.
Both of our '86 Civic Wagons averaged a little over 34 mpg through their 200K+ lives, and either could easily do 40 mpg on my commute.
A really bad tank might get you down to 30 mpg.
These were cars with room for four adults and their gear.
Honda sells nothing like this in the US anymore, nor does anyone else.
These were light, plain cars, with a rather harsh ride and high interior sound levels by current standards.
Also, these things could not possibly have met current impact standards.
Still, light and simple yields good fuel economy.
Also, these 1.5 liters were smoother than any Honda we have had since.