4S dealership records are directly connected to the manufacturer's database, making the data hard to tamper with and the most reliable, with original parts guaranteed; third-party repair shops usually are not connected, making their data unverifiable. Therefore, we only consider the connected records from 4S dealerships as valid historical documentation.

We use a calibrated high-precision paint thickness gauge to take multiple measurements on at least 13 metal surfaces of the entire vehicle. The original paint thickness of mainstream Chinese models typically ranges from 90μm to 150μm. If any area exceeds 200μm or even reaches over 500μm, we will directly conclude that the area has undergone bodywork and filler repair.

Chinese passenger cars produced after 2005 have fully transitioned to asbestos-free brake pads, clutch plates, and gaskets. However, for export to countries with strict regulations, buyers must pay for sampling and testing by a NATA-accredited laboratory before shipment, and obtain an asbestos-free certificate.