Once the car system (especially in a closed ecosystem) undergoes a major version upgrade, its bootloader is usually locked, preventing downgrades. If this happens, there is basically no solution in an overseas environment. Therefore, we strongly warn: do not blindly insert a USB drive to upgrade while offline.

A proper inspection relies on equipment, not just eyes. The inspector should use a paint thickness gauge to measure 50-60 points across body panels; original paint is typically 80-150 microns. An OBD diagnostic scanner reads stored and pending fault codes across all control units, and for EVs it also reads battery state of health and charge cycle counts. The car must go on a lift for the underbody check: frame rails, suspension components, oil leaks and accident repair marks are only visible from below. A battery tester checks starting voltage and charging system health, and a tread depth gauge documents tire condition. Ask for the report to include raw readings and dated photos rather than a simple pass/fail summary - that is what makes it verifiable.

Based on practical risk assessment, we strongly recommend setting aside 3% to 5% of the car price as a buffer fund for even the highest-rated used cars, to cover oil changes, new tires, minor shipping scratches, and local inspection labor costs.