We maintain an absolute skeptical attitude. In addition to regular visual inspections, we focus on checking for sediment accumulation around the sunroof drainage channels and look for water stains under the A-pillar trim and front floor mats. This is the only effective physical evidence to determine if the sunroof drainage holes are blocked, leading to hidden leaks.

The "usage type" section on the vehicle registration certificate has legal validity. Any vehicle that changes from "commercial" to "non-commercial" has a usage intensity far exceeding that of personal vehicles, and we will label these prominently. Such vehicles are usually cheaper but have more severe mechanical wear.

We will use a megohmmeter (insulation resistance tester) to measure the insulation resistance of the high-voltage bus. If the resistance value is below the national safety standard, it indicates a risk of leakage, and the vehicle will be deemed unqualified.