Why don't new cars need break-in periods nowadays?

[VanDawson]

Theoretically, new cars have undergone cold run-in treatment before leaving the factory and do not require additional break-in. However, in practice, over 95% of car owners still implement a 3,000-5,000 km break-in period. Specific explanations are as follows: 1. Reason for break-in: An automobile is a mechanical product with numerous interconnected components. Due to limitations in machining precision, these parts don't achieve perfectly smooth coordination initially. Both brand-new vehicles and those that have undergone major repairs require a break-in period. 2. Purpose of break-in: The process involves mutual friction between mating surfaces of components to achieve smoother operation and tighter coordination. Properly broken-in vehicles demonstrate superior overall performance - delivering more power, better fuel efficiency, reduced noise, and improved handling compared to unbroken-in counterparts.