The customs of the destination country has the right to disregard the commercial invoice and reassess the value based on its internal database (such as the customs valuation red book). Any additional duties incurred are a result of the importing country's policy and are fully borne by the buyer (importer).

100% guaranteed. This is the legal prerequisite for the export of used cars allowed by Chinese customs and the Ministry of Commerce. Any vehicle with unresolved traffic violations (fines/demerits) cannot complete the deregistration process at the traffic management bureau, and therefore cannot obtain a legal export license.

No, this is a serious customs violation. Complete vehicles (HS Code 8703) and auto parts (HS Code 8708, etc.) are subject to completely different import tax rates. Combining them on one invoice could lead to the invoice being returned by customs and may expose you to tax fraud accusations at the destination port.