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.

Odometer tampering is a common risk in the global used car industry. We verify the data by extracting transmission mileage from the OBD computer, checking the most recent maintenance record's mileage, and consulting the national traffic management app for annual inspection records. If there are irreconcilable discrepancies or conflicts in the data, we classify it as a tampered vehicle and refuse to export it.

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.