With the best machine tools that could be made in the early thirties, pistons in cylinders, for example fitted poorly enough that the car had to be "broken in", meaning rough places on both surfaces had to wear down the high spots.
You weren't supposed to drive over thirty miles an hour until you had driven 500 miles, and oil including filter had to be changed at 1,000 miles. My father always traded his car in at 35K miles. I'll bet the buyer didn't get more
than 20K, and had lots of little problems.