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.

Due to legal restrictions preventing unregistered vehicles from high-speed driving on public roads in China, most of our dynamic tests are conducted in a closed area (with a maximum speed of around 60 km/h). This is sufficient to test for suspension noise and low gear smoothness, but it cannot simulate high-speed wind noise and tire balance vibrations at 120 km/h.

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.