I had a 1979 Datsun 210 4 cylinder 5 speed in the Navy, I got 40 city and 52 highway.
The ad says 35 city and 48 highway, but mine did better, but I did tune it myself always:
https://www.ebay.com/itm/401582799341
I love old cars and the ease of working on them. I had several old Datsuns, 1966 through 1970. Already had great mileage on them, but I enhanced them. Ported out and polished the intake ports on the cylinder heads, likewise with the carburetors and balanced them. Tuned the camshaft and valves. My 1600cc engines outperformed the 2000cc engines of friends. And my 2000cc engines with SU carbs outperformed other friend's cars with 2000cc engines and Solex carbs. All while getting over 35mpg. Also worked on 1960's era Chevy engines. I don't work on modern engines, too difficult with all the smog and electronics crap on them.