Rust is one of the most underestimated problems in remote buying. Request specific evidence: photos of the underbody, wheel arches, door sills, and around the windshield seal; close-ups of suspension mounting points; and ideally paint thickness readings across panels (factory paint is typically 80-120μm; heavy patches suggest bodywork). Northern Chinese cars may have winter road-salt corrosion; coastal cars can show surface rust on exposed metal. Surface rust on exhaust and bolts is normal—structural rust on frame rails, subframes, or brake lines is a deal-breaker, especially if the car is headed to a humid or coastal market. Have the inspector tap suspicious areas during the video call: flaky or bubbling metal sounds hollow. Walk away if the seller refuses underbody photos.

Heavy-use vehicles often look clean in photos but show specific wear patterns. Here's what to check: 1. Rear sag and suspension: ask for a side-profile photo of the car on level ground. If the rear sits noticeably lower than the front, the rear springs or shocks may be worn from constant heavy loads. Compare with factory ride height specs. 2. Pedal and seat wear: accelerator and brake pedals with polished metal patches, and a driver's seat bolster that is flattened or cracked, indicate high mileage or intensive commercial use — even if the odometer says otherwise. 3. Hitch and tow bar marks: check the rear bumper area in close-up photos for scratches, bolt holes, or a removed tow bar mount. Ask the seller directly whether the car ever towed. 4. Underbody and frame: request underbody photos. Look for bent or scraped crossmembers, fresh undercoating hiding damage, or uneven tire wear across the rear axle. 5. Data check: many ride-hailing cars in China have records in maintenance databases — a professional inspection agency can flag cars with commercial fleet history. If the seller refuses underbody or close-up photos, treat it as a warning sign and consider another vehicle.

An OBD scan is one of the most cost-effective tools in a remote pre-purchase inspection, but you need to know what it can and cannot tell you. What it reveals well: current and stored fault codes across the engine, transmission, ABS, airbag, and body modules. A car with dozens of cleared codes in multiple modules may have electrical problems or a history of tampering. It also shows readiness monitors — if all monitors show 「not ready」 on a car that claims to be freshly serviced, the codes were probably cleared recently to hide something. What it reveals with the right software: live data. You can watch engine idle stability, coolant temperature under load, transmission shift behavior, and battery cell voltages on EVs. Abnormal fuel trims or misfire counters can flag worn injectors or coils before any warning light appears. What it cannot do: prove real mileage (odometers can be corrected digitally), detect physical accident repairs, or judge paint and rust. Practical advice: ask your inspector for a full-system scan report with screenshots, not just a 「no codes」 verbal summary. For Chinese brands, make sure the tool supports their protocols — mainstream scanners cover BYD, Geely, and Chery well, but some small brands need brand-specific software.