For gasoline cars, insist on a compression test: each cylinder should read within 10-15% of the others, and the actual values should match factory specs for that engine. A single low cylinder points to worn rings or valve problems that idle checks will never reveal. A leak-down test goes further. It pressurizes each cylinder and measures how much air escapes and where. Air hissing from the oil filler cap means ring wear; from the intake or exhaust means valve issues; bubbles in the radiator coolant mean a head gasket problem. This is the single most revealing test for engine condition. Also request OBD scan data with freeze-frame records, a coolant system pressure test (to catch hidden leaks), and an inspection of the timing belt or chain condition with service history. For electric vehicles, compression tests don't apply — instead ask for a battery health report from the BMS, motor insulation readings, and a road test logging any inverter or drive-unit fault codes. A written report with photos or video of each test is essential evidence for your records.

Odometer fraud exists everywhere, but cross-checking several data points makes it hard to fake: 1) Maintenance records: ask for service history with mileage entries. Gaps or resets are red flags. 2) Tire wear: a car showing 30,000 km should not have nearly bald tires. Compare tread depth against the claimed mileage. 3) Pedals, steering wheel, and seat bolsters: heavy wear on these with low odometer readings is a classic mismatch. 4) Diagnostic scan: request an OBD readout. Many control modules store mileage data internally — if the ECU shows 120,000 km while the dash shows 40,000, you have your answer. 5) Vehicle history report: in China, apps and platforms can pull insurance claim records and registration history, which often reveal the true mileage trail. Always request a live video showing the odometer with the engine running, and have the number written into your contract.

Start with the business license: every legitimate Chinese company has a Unified Social Credit Code. Ask for a copy and verify it on the National Enterprise Credit Information system or via your freight forwarder. Check that the business scope includes 'used car export'—this requires specific qualifications. Next, look for proof of substance: a real office or yard (verify via live video call, not pre-recorded), staff answering on Chinese business platforms like WeChat with consistent branding, and a corporate bank account in the company's name—never pay a personal account. Cross-check trade history: ask for recent shipping documents (blurred bills of lading with customer info hidden), references from buyers in your region, and whether they hold export licenses issued by Chinese commerce authorities. Red flags: prices far below market, pressure to pay quickly, refusal of video calls, or bank accounts in third countries 'for convenience'. Take your time—real exporters pass these checks easily.