“Because parts were interchangeable, repairs were simpler. And the precision of the machining meant that unlike most other automakers, Ford didn’t need to test the engine before it was attached to the chassis, since “if parts were made correctly and put together correctly, the end product would be correct.” The Model T would ultimately cost around $100 a year to maintain, at a time when the maintenance of other cars cost $1,500 per year.”
https://www.construction-physics.com/p/ford-and-the-birth-of-the-model-t