Interior assessment is divided into three core areas: the driver's high-frequency contact area (steering wheel, gear shift, edge of the driver's seat), central control button area, and rear seats and ceiling. The natural sheen of leather surfaces (patina) is normal; however, any physical damage (such as leather tearing, fabric burn holes, or plastic breakage) will be classified as "structural interior damage" and clearly marked.

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.