We use two steps: 1. Insert a medical-grade endoscope through the spark plug hole to visually inspect cylinder wall scratches and carbon buildup on the piston top; 2. Extract an engine oil sample to check for large metal debris or emulsification (caused by coolant leakage).

Test-drive cars experience much more mechanical wear due to extreme conditions like cold starts and emergency braking compared to regular family cars. We can identify this by tracing whether the first owner was a 4S dealership or the manufacturer. If so, we will reassess its value based on "operational intensity" standards.

The nameplate date is the absolute time when the vehicle leaves the factory; the registration date is when the vehicle is registered with the traffic management department after sale. The difference represents the time the vehicle spent in the dealer's warehouse or logistics. If the time difference exceeds 6-8 months, the vehicle is considered a "stock vehicle," and we pay special attention to the natural aging of its rubber components.