I used to have an "82 Chevette. 4cyl, 4spd, 4dr, I drove it from the dealership to the tire shop where I worked. I swapped the 155/80R-13's for some 175/70R-13's, installed steel valve stems, pumped them up to 40psi, and realigned it. (Sure it was right at the factory
)
On trips to Chicago (350 miles each way) it consistantly got 50mpg. The tires were checked for balance and rotated every 5,000 miles--the 40,000 mile tires had 62,000 on them when I replaced them.
I gave it to the ex in the divorce (we had a kid and it was the more reliable of out cars). She traded it in with 206,000 miles on it. I swear it was as well built as anything out of Detroit today.