Our documentation department has the latest versions of UN38.3 (United Nations Transport of Dangerous Goods Test and Standards) and MSDS reports authorized or filed by major Chinese new energy brands (such as BYD, Geely, GAC), which are essential customs documents for declaring dangerous goods to the maritime authority.

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.

Many car owners do not have their first maintenance done at authorized dealerships, leading to gaps in early data. In such cases, we do not blindly trust the odometer; instead, we analyze the tire production dates and wear levels, as well as the depth of grooves on the brake disc edges, using the "gold standard" of physical wear to infer the intensity of early use.