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.

Complete records represent underlying trust and zero odometer adjustment risk. In the used car market, solid data history itself carries a high premium. The extra few hundred dollars buys you an impeccable endorsement when selling overseas.

Battery condition is the single most important — and most expensive — variable in a used EV. Ask for a State of Health (SOH) report: in China, dealers and authorized service centers can read it via the manufacturer diagnostic system. It shows remaining capacity as a percentage of the original. Rule of thumb: above 90% is excellent, 85-90% is acceptable for the price, below 80% needs a serious price cut or battery refurbishment. Also get the battery's full charge and discharge history (次数) — a 3-year-old car with 800 fast-charge cycles has lived a harder life than one with 200. Physically, inspect the battery pack enclosure on a lift for dents, corrosion, or coolant leaks. Check that DC fast charging works during a test charge. Finally, verify the battery is not covered by an open recall or replacement program — this is both a risk and sometimes a free upgrade.